Tia Lightning thought back to what Kili Surtr Muspelheim had told her at the Castle of Mirrors.
"As things stand, Tia, Yggdrasil cannot be defeated no matter what. But if you give up your human identity, there might be a path to hope."
"Eh...?"
Tia stared blankly at Kili.
The hall all covered with mirrors gave an illusion of infinite space. At the same time, it also produced countless reflections of Tia and Kili.
An uncountable number of virtual images—Facing the black-haired girl was the girl with two red horns on her head in great unease.
"I originally planned to raise you as the trump card for taking down Yggdrasil. Your horns are also an organ existing for the sake of opposing Yggdrasil."
"These..."
Putting her hands on her head, Tia touched her two red horns.
"Indeed, this is an organ connected directly to the brain, which is why I can't put it on myself. Manipulating your own brain will mess up your concentration in the process, causing the control of biogenic transmutation to fail."
"Then... If Tia works hard, Yggdrasil can be defeated?"
Tia asked timidly but Kili shook her head.
"No, I haven't finished with your treatment, so those horns cannot function as intended yet. But if you wish, I could perform the final treatment for you."
Staring into Tia's eyes, Kili made this proposal.
"Then like this... Tia will be able to help Yuu and the others?"
"If all goes well. After all, I can't guarantee success since this is the first time, but if your horns function as planned, Yuu and the others have a shot at victory. However—"
Kili paused and narrowed her eyes.
"—The moment Yggdrasil is defeated, you will surely become a dragon transcending the boundaries of Ds and humans."
"...!"
Tia gasped and took a step back.
"Don't worry, I won't force you, so no need to be afraid. I'm no longer a puppet controlled by Mother. I will freely decide my 'way of living' according to my own will, so please make a choice according to your own wishes."
Kili's expression turned gentle and she smiled at Tia.
"Kili..."
It was a gentle smile that Tia had never seen on Kili's face.
"Yuu said before that how one lives their life is more important than what they are. What matters is not the identity of your existence, but what you want to do."
In the middle of this predicament with Yggdrasil's branches flooding towards us, I was stunned on the spot with all eyes on me.
My secret had been revealed.
The fact that Yggdrasil was stealing my body had been exposed.
Finally, she still ended up finding out. Clearly when Mitsuki was the one person I did not want to know this secret.
"Mononobe-kun, tell me the details."
"I want to hear your explanation."
Firill and Ariella approached to question me.
"Yuu, tell Tia the truth..."
Tia stared at me with determination, refusing to back down by a single step.
"I'm interested in the details too."
Kili urged me to explain with her gaze.
By this point, I could not cover things up anymore.
Gritting my teeth, I searched for an answer to give them, but—
"Mononobe Yuu, clearly the only choice is to tell them. The weapons you used so far to defeat dragons were created based on data provided by Yggdrasil. The price you paid is that your body is now about to be stolen."
Lisa's fictional armament fired a flash of light, attacking the branches above while she spoke to me.
However, what she said felt strange to me.
"Huh...?"
Hearing her say that, Iris stared wide-eyed from the side.
The price paid under the deal with Yggdrasil was the loss of my memories, while taking over my body was the trap it had laid. These two were a bit different in meaning.
When my thoughts reached this point, I noticed something. When Tia overheard my conversation with Lisa, the subject of memory loss was not mentioned.
Then at least the worst situation—that I was not the "Mononobe Yuu" whom Mitsuki knew—Perhaps this one fact could still remain hidden to the very end.
...Thank you, Lisa.
While feeling grateful for Lisa's quick thinking, I started to explain to Mitsuki and the others.
"Just as Lisa said, I secretly made a deal with Yggdrasil to defeat dragons. But there was apparently something similar to a computer virus in the data that was sent, so gradually—and right now—I'm being invaded by Yggdrasil."
Omitting the memory part, I revealed the truth.
"To defeat dragons...? Could it be that three years ago, Nii-san, you—"
Mitsuki murmured blankly.
Three years ago, to protect my hometown, I used a power, which was normally impossible, to repel Hekatonkheir. This was done exactly by relying on anti-dragon armaments created from the weapons data obtained from Yggdrasil.
Smart as she was, Mitsuki seemed to recall that immediately.
"Yeah, the fight against Hekatonkheir three years ago was the first time."
I nodded in response to Mitsuki, despite knowing that Mitsuki would feel heavily guilty as soon as I confirmed it.
However, this was much better than telling her "the price was memories."
As long as Yggdrasil was neutralized, its invasion of me would presumably stop, but there was no guarantee my memories would recover.
When it was impossible to recover the real "Mononobe Yuu"—I did not want to bring despair to Mitsuki.
"Mononobe-kun... Why did you hide this? If the weapons for defeating dragons is the reason, then you must have made a deal again back when I was in a crisis, right?"
Firill glared at me angrily.
"...Sorry, because I didn't want you to feel responsible or in debt. Also, I only found out recently I was being controlled. I never expected things to turn out this way."
I bowed my head and apologized to Firill.
Seeing me like that, Ariella scolded:
"I understand how you feel, Mononobe-kun, but it pisses me off that we're the only ones kept in the dark. From the way it looks, Iris and Ren also knew in addition to Lisa, right?"
Iris looked down in shame when Ariella glanced at her, but Ren met her gaze and pointed her finger in the air.
"Mm."
I took a closer look. Because fewer people were attacking, the branches were gradually closing in.
"—Meaning it's not the time for arguing? Can't be helped, I'll complain properly later."
Ariella returned to attack after glaring at me.
"Me too... I have things to say but I'll hold back for now."
Firill turned her back to me and started attacking the branches again.
"—As thanks for letting me hear something interesting, I'll help out a bit."
With a wave of her hand, Kili incinerated branches with a red beam of scorching heat.
But in this situation, Mitsuki and Tia did not take their gazes off my face.
I saw Mitsuki biting her lower lip, shoulders trembling, a tear sliding down her cheek.
"M-Mitsuki—Don't cry. It's really my fault, I'm sorry—"
Even I was surprised at how shaken I was inside. I kept apologizing to her. To me who had lost all memories beyond three years ago, she should not be someone "special"... But my heart was shaken to a ridiculous degree.
"...Nii-san, you need not apologize. I am crying because I am too useless... This fills me with chagrin... So do not worry about me."
Mitsuki spoke hoarsely and brusquely wiped her tears away with her hand.
"Putting that aside, please allow me to confirm one fact. Is what you said just now everything?"
"Eh..."
My heart pounded like crazy.
"I knew long ago that you were hiding things from me, Nii-san, but I also understood you were hiding desperately... So I deliberately refrained from asking, but this incident has filled me with extreme regret. So this time, I will muster my courage to ask you, Nii-san, are you still hiding things from me?"
Mitsuki asked me with conviction.
I thought I had concealed things well, but now I knew I was totally seen through.
More than anyone else, Mitsuki knew this person of "Mononobe Yuu." She knew everything about me that my current self had forgotten. In front of someone like that, of course hiding would not work.
"...Yes."
I nodded to confirm Mitsuki's question, but I continued:
"But I can't tell you, Mitsuki."
I prepared myself and asserted clearly.
"Why?"
"I still can't say it yet."
I shook my head and stared into Mitsuki's eyes that were red from crying.
"Then when can you say it?"
"—Once I've retrieved everything."
I gave this answer because I could not think of another way of saying it.
"Even if I ask you what you mean by that, you will not answer, right?"
Mitsuki smiled wryly with feelings of resignation.
"...Sorry."
"Very well—Because I know how stubborn you are, Nii-san, I will not force the matter at this time. However, one final matter, please tell me—Tia-san said that Yggdrasil must be defeated now. Is that true?"
Mitsuki's expression tensed. She asked me in a tone of suppressed emotion:
"...It's true that Yggdrasil's interference in me has strengthened, but I won't get controlled by it immediately, so there's still time. We should retreat temporarily."
To be honest, I had a feeling that the final time limit was not far away, but I answered this way to reassure Mitsuki. Because right now, we were totally out of options.
I was admittedly happy that Tia said she would protect me, but right now, we should retreat and request reinforcements from Midgard. With a larger force, it might be possible to handle the branches' rate of growth.
"I understand. Indeed, as the captain of the Dragon Subjugation Squad, there is no alternative as a decision. Well then—"
Mitsuki paused halfway then turned to face Shinomiya-sensei.
"Shinomiya-sensei, forgive my willfulness, but I, Mononobe Mitsuki, hereby relinquish my duties as captain of the Dragon Subjugation Squad."
"What are you suddenly..."
Shinomiya-sensei was shocked.
The others, still attacking branches, also stared in Mitsuki in surprise.
"Mitsuki-chan...?"
Troubled, Iris called her name, tilting her head in puzzlement.
"Mitsuki..."
Tia also showed doubt on her face but I could also see her trying to figure things out.
But ignoring everyone's reactions, Mitsuki turned to face me.
"Starting now, I will only fight as your younger sister to protect you, Nii-san. I will absolutely not retreat."
"H-Hey—I said there's still time, right?"
"Nii-san, do you think lying can deceive me?"
As though having come to a realization, Mitsuki showed a refreshing smile while glaring at Yggdrasil's branches extending from the western sky.
"Hold on, what do think think can still be done in this situation? If there's a solution, I wouldn't call for a retreat."
The way I saw it, Mitsuki was going to attack recklessly without a plan. I made haste to stop her.
"Indeed, given the current situation, marching forward while keeping sufficient distance from the interference range will be impossible. However, much can be done as long as one disregards one's safety. Such notions would disqualify a commander... But right now, I am merely a younger sister, nothing more."
Mitsuki smiled as though telling a joke and continued:
"By eliminating branches in the minimum range ahead and flying at high speed, it might be possible to advance."
"What...? But if you get caught in Yggdrasil's interference range, even if just a little, you'll crash immediately, right? It's too dangerous!"
I instantly yelled in objection.
"—I know, which is why I intend to go alone. I will find a way to reach a spot where I can aim at Yggdrasil directly, to destroy the base of the branches. That way, I should be able to buy quite a lot of time before it grows again. Nii-san, you and the others will use that window to attack."
Mitsuki's expression showed that she was completely prepared already.
"Don't do something stupid like that—"
I reached out, trying to stop Mitsuki, but she was surrounded by a layer of wind, deflecting my hand.
Everyone tried to call out and stop her with frantic expressions.
But before anyone could make a sound, she acted even faster.
"Wait!"
Mitsuki hovered into the air, but Tia crashed into her, wrapped in her own layer of wind.
"Kyah!?"
Entangled together, the two girls fell to the ground.
"Tia-san, let go of me!"
Mitsuki tried to pull off Tia who was hugging her waist but Tia resisted desperately and yelled:
"Don't do that, Mitsuki! Leave it to Tia! If it's Tia, it will definitely succeed!"
"Huh...?"
Hearing what Tia said, Mitsuki stopped.
"Sorry, Tia should have said this earlier, but Tia finds the current life so happy... Don't want any change... So Tia could not gather enough courage. But Tia has decided now."
Tia separated from Mitsuki who had stopped resisting, then looked at Kili.
Originally helping out with eliminating branches, Kili stopped and faced Tia at this time.
"Is that right? Tia, you will be choosing your way of living."
Kili spoke gently to Tia.
I did not know what was going on, but my heart was in turmoil.
Tia nodded and said with a voice of determination:
"Please, Kili, give Tia the power to fight Yggdrasil."
"Got it, then I'll perform the final treatment for you."
Kili slowly approached Tia.
"Hey, what treatment? What are you planning to do!?"
Unable to grasp the situation, I yelled acutely at Kili.
"—I will make Tia's horns complete."
Kili placed her palm on the pair of horns on Tia's head and gave me a brief answer.
"Make her horns complete... What on earth is—"
"Tia is the child I raised to become the trump card against Yggdrasil. These horns were created as an organ for opposing Yggdrasil. Although the horns currently don't function, so long as Tia wishes, I can make these horns complete. This was what I proposed to her at the amusement park."
Staring at Tia's horns, Kili quietly explained.
So that was what they talked about in the Castle of Mirrors that time—
"...Tia has been brooding the whole time after returning from the amusement park, like she was in a dilemma... afraid of something. Is that final treatment something frightening to Tia?"
I stared at Kili and questioned her in a fierce tone of voice.
"Yes, I don't know what will happen if it fails. Even if it succeeds, Tia will become an existence transcending the boundaries of what it means to be a D. Based on Midgard's definitions, she might end up categorized as a dragon."
Hearing Kili's words, Iris' shoulders shuddered.
As a D who had transcended boundaries, Iris must have felt greatly shaken inside after listening to Kili.
"I won't let Tia do something so dangerous!"
"That's not for you to decide."
Just as I tried to take a step forward, a small explosion detonated in front of me.
"!?"
I guarded my face with my hand and jumped back reflexively. The searing pain on my skin forced me to frown.
"Don't get in the way, Yuu. Even you have no right to stop Tia from choosing her own path."
Exuding off intense killing intent, Kili restrained me from taking action.
The surrounding temperature rose. Sweat was seeping out of my forehead and neck. She must have deployed Muspelheim.
What should I do...? Stopping them would require the determination to murder Kili.
Just as I hesitated, Tia smiled at me.
"Don't worry. Because no matter what Tia becomes, Tia will be still the one who loves Yuu most—Yuu's wife."
Then the dark matter generated in Kili's hand melded with Tia's horns as though getting sucked in.
"—!!"
The two horns shone with dazzling light while Tia emitted a deafening scream.
Blinding light and an extended scream.
"Tia!"
Ignoring Kili's deployed Muspelheim, I dashed towards Tia.
The final treatment probably ended in an instant—Kili did not stop me. After she put down her raised hand, Tia immediately collapsed on her knees.
As though sliding, I caught Tia's petite body, feeble and drained of strength.
"Stay with me! Tia!"
I called to her but Tia seemed to have lost consciousness. No reaction. Her two red horns also showed no change in appearance.
"Tia-chan, are you okay!?"
"Tia-san!"
Iris and Mitsuki rushed forward from behind, peering at Tia's face.
Unable to leave their positions from eliminating branches, Lisa and the others looked in our direction with paled faces.
I looked up and glared at Kili.
"What happened to Tia? Did it—fail?"
"Can't tell until Tia wakes up. The completed horns have connected to Tia's brain, so as long as she is able to withstand the strain, she'll surely—"
Just as Kili spoke in a praying tone of voice, Tia stirred.
"Mm..."
A faint sound came Tia's pink lips. A spark of lightning flashed and popped near her red horns.
"Tia can hear..."
Tia spoke hoarsely while opening her eyes slightly.
"Thank goodness, you woke up."
I breathed a sigh of relief, only to see Tia staring at me.
"Tia can hear a cold voice calling Neun... Neun... Is this the voice of Yggdrasil that's troubling Yuu?"
"What...? You can hear it too, Tia?"
I asked in surprise.
Just as Tia said, Yggdrasil's voice was still sounding in my mind right now.
"Yes... So this is Yggdrasil... Yuu's enemy."
Tia spoke as though in the middle of a dream and stood up.
"Tia?"
I noticed Tia acting a bit strange and called to her but she focused her gaze westward towards Yggdrasil instead of answering. The electrical sparks scattering over Tia's head in the horns' surroundings gradually increased.
"...Stop making Yuu suffer, be quiet!!"
The instant Tia yelled, electricity exploded nearby.
"What!?"
Boom, Shinomiya-sensei's laptop exploded. The surroundings suddenly felt quiet.
"Yggdrasil's voice... disappeared?"
I muttered blankly. Yggdrasil's voice was originally loud enough to feel noisy, but now, no matter how I much I focused my mind in order to listen, I could not sense the voice anymore. The sense of dissonance in my left arm also disappeared.
"Looks like it succeeded."
While everyone was feeling troubled, Kili was the only one to show a contented look.
"What did Tia do?"
I demanded an explanation from Kili.
"—What Tia has constructed is an electromagnetic barrier that could probably block out Yggdrasil's interference completely. And if my predictions are correct, Yggdrasil is currently unable to steal Tia's dark matter. Just by maintaining this barrier, your side will be able to enter Yggdrasil's interference range."
"What... Tia is now capable of that kind of thing?"
I gasped and asked.
"Yes. Speaking of which, the reason why Yggdrasil can steal dark matter is because electrical signals simulating thoughts will have more interference strength than weak mental waves. That's why I've given Tia a renewed organ capable of outputting thoughts as electrical signals."
"Namely... those horns?"
I looked at Tia's horns, surrounded by glowing electricity.
"Also, Tia has a habit of subconsciously transmuting dark matter into electrical currents. When the dark matter is transmuted emotionally, it becomes equivalent to thoughts encoded into electrical signals. This further strengthens Tia's interference strength, repelling Yggdrasil's interference. This is the truth behind the electromagnetic barrier."
Thinking back, Tia really did have a habit of generating electrical currents when emotional. That was probably why Kili had chosen Tia.
After listening to that, Tia held her head and asked Kili:
"So... If it's Tia right now, Tia can protect Yuu and the others?"
"That's right. As long as you think intensely and generate dark matter persistently, the electromagnetic barrier will be sustained. As long as they stay inside the barrier, the dark matter of Yuu and the others will be free from interference."
"Got it... Tia will work hard."
Tia nodded and moved her hand away from her head. I saw pearl-like sweat on her head.
It was probably causing her quite a lot of strain. Bestowed with an organ that was not inborn, it was only natural for her body to have a rejection reaction.
But Tia steadied her shaking body with her legs and spread the pair of red wings that was her fictional armament.
"Yuu—Everyone follow Tia. Tia will take everyone to Yggdrasil."
Tia spoke with unshakable determination.
Will you be okay? I could only swallow these words.
Because I quickly understood that it was a meaningless question. Asking it would be a waste of time.
I could see that she was not okay at all. She was clearly forcing herself.
In reaction to becoming like this—No, she had chosen to do this.
Simply for the sake of protecting me.
Lisa silently approached Tia and hugged her.
"—I know, then I will count on you, Tia-san. However, please focus on maintaining the barrier. I will fly and carry you."
"Thank you... Lisa."
Tia dispelled her fictional armament and held onto Lisa's waist.
"...I will carry Onii-chan."
Feeling someone pull my right hand, I turned my gaze to see Ren looking up at me.
Ren's cooperation with me was the key to the next part of the plan, so it was probably better that I traveled with her.
"Okay, I'm counting on you."
I held Ren's hand. Having confirmed the situation, Mitsuki walked over to Iris and took her hand.
"Then I will be responsible for Iris-san's transport. So this is it—Shinomiya-sensei, we are setting off."
Holding the wrecked laptop in her hand, Shinomiya-sensei was looking a bit lost. Then at this time, she smiled wryly and acknowledged.
"Okay... Looks like I can't provide support anymore, so I'm leaving the rest to you. Captain of the Dragon Subjugation Squad—Mononobe Mitsuki."
Shinomiya-sensei intentionally added the title when addressing Mitsuki.
Having just declared she would relinquish her duties, Mitsuki made a slightly embarrassed look before saluting with upright posture.
"Affirmative. I will fulfill my duties as the captain of the Dragon Subjugation Squad."
Gathered around Lisa, who was carrying Tia in her arms, we flew through the night sky.
Yggdrasil's branches were growing at a frightening rate in front of us.
Although it was impossible to measure the exact interference range, the area under the branches was most likely its territory.
We cautiously lowered our altitude and rushed into Yggdrasil's interference range.
—No change.
Having confirmed there was no interference in our fictional armaments or any signs of impedance to transmutation, we increased our altitude and flying speed. The sky glowed white faintly. Dawn seemed to be approaching.
Flying in the lead while carrying Iris in her arms was Mitsuki. Holding the rear was Ren, transporting me, with Kili flying by our side.
"How unexpected. I can't believe you came along, Kili."
Flying in the sky with Ren holding my hand, I spoke to Kili beside me.
"Let me enjoy the show to the very end since I'm already here. Of course, I won't just watch. I'll offer a helping hand and won't drag you down, so relax."
"I don't doubt your abilities, but I'll be watching you to see if you have any ulterior motives."
I declared to Kili that I refused to trust her.
"Fufu, I don't mind. That means you'll have your eyes focused on me."
Kili smiled confidently.
"...!"
Her smile was inexplicably dazzling and stunning, rendering me speechless for a moment. Sure enough, this girl was not easy to deal with.
"However, you should probably focus your attention on Yggdrasil rather than me. Once it realizes its interference over dark matter isn't working, it will surely take other measures."
Just as Kili reminded me to pay attention, Mitsuki yelled from the front:
"Heads up, Yggdrasil's branches are showing changes! Be careful, everyone!"
I hastily looked up to notice that we were already under a canopy made from Yggdrasil's branches.
These capillary-like branches blotted the sky, writhing in a sinister and spooky manner. Numerous branches, as sharp as spears, were attacking our position.
"All units deploy shields! We will break through by force!"
Mitsuki commanded in a sharp voice.
"Looks like it's my turn."
Kili grinned proudly and raised one hand to the sky.
"—Such flammable-looking branches won't even manage to enter my Muspelheim."
The approaching branches suddenly caught fire, burning into tiny particles of ash.
She had most likely deployed an invisible barrier of high temperature in the air.
Mitsuki and the girls also deployed barriers of wind, but all the branches were burnt to ash before reaching them.
Under the gradually brightening sky, the outlines of Mount Fuji's tall appearance and the towering Yggdrasil were gradually coming into view.
"Target confirmed! Once we pass over Mount Fuji, our distance to the target will be 10 kilometers or so—Sniping distance. Iris-san, show time for you!"
"Yeah!"
Iris nodded in response to Mitsuki.
"Once we pass Mount Fuji, Lisa-san, Iris-san and I shall attack the main body in full force while trying to get even closer. Firill-san and Ariella-san, continue to deploy shields. Nii-san and Ren-san will prepare to scatter Ether Wind after the main body is destroyed!"
"Yes!"
I answered and made eye contact with Ren, exchanging nods in acknowledgement.
"Huh? What about me?"
Without being called on, Kili asked, prompting Mitsuki to reply in a cold voice:
"If you wish to help, please participate in attacking."
"Oh dear, it feels like you're not expecting much of me?"
Kili grumbled with dissatisfaction.
Immediately, Iris, who was carried by Mitsuki, looked back and smiled cheerfully at Kili.
"It's not like that, Kili-chan, let's do our best together!"
"...Y-You're really good at getting others caught in your pace. Fine, whatever. Having created this chance for Tia, even without being told, I seriously intend to go on a rampage."
Kili spoke with violence in her eyes.
The snowtop of Mount Fuji was before us, but the branches suddenly stopped attacking.
Just as it seemed like Yggdrasil had given up on obstructing us with branches, Lisa yelled acutely.
"Look quickly! Yggdrasil's shape—"
Located on the far side, Yggdrasil's towering trunk was gradually expanding unnaturally in the middle.
Then bizarre and thick branches were forced out from the bulging portion.
The sun seemed to rise at last and the sky brightened all at once. Behind us, the sun's rays from the east were making us slightly dizzy.
"Everyone! Go down rapidly right now!"
Just at this moment, I heard Tia shout anxiously.
"Yggdrasil's target is Tia!"
Hearing Tia's urgent voice, everyone lowered their flying altitude without fully understanding what was going on.
In the next instant, a flash of blinding light rushed past us above.
"W-What was that!?"
Firill cried out in surprise.
"No idea, it seems like something flew out from Yggdrasil..."
Ariella had not figured out the situation either.
"Dodge quickly! It's aiming again!"
Tia yelled again.
"Descend further!"
Mitsuki instantly ordered us.
After we obeyed, another flash of light passed over us.
"That light... Its speed... The power of electrical interference—It might be an object shot at high-speed using electromagnetic induction."
Flying ahead, Mitsuki said in a stiff tone of voice.
"Isn't that a railgun!? Isn't it impossible to dodge if something like that is aiming at us!?"
Lisa yelled anxiously but Kili interjected confident after hearing her:
"—Don't worry. Tia noticed the attacks in advance, twice already, right? Tia, did you feel anything?"
Tia nodded lightly at Kili's question.
"Yes, there's a dangerous feeling."
"I knew it. Tia's horns are also quite sensitive towards external electromagnetic waves. Although it wasn't an ability by deliberate design, as long as we have Tia, we should be able to dodge."
After Kili said that, Tia made an alarmed expression and yelled:
"It's coming again!"
"All units dodge right!"
Mitsuki instantly commanded.
I could see a glowing ball shot out from the branches protruding from Yggdrasil's trunk.
Just as I was thinking that, a blinding light flashed past our left.
As Lisa said, it would be impossible to dodge visually.
But such a powerful attack could very well get me caught up in it too. Yggdrasil seemed quite shaken when harming me in Midgard. Although the reason was unknown, it looked like it wanted to obtain me intact.
Nevertheless, Yggdrasil seemed to be prioritizing the elimination of Tia over ensuring my safety. Perhaps that was how much of a threat it viewed Tia.
"It's not over!"
We listened to Tia's directions and steadily closed in on Yggdrasil while evading the railgun shots.
Finally, we passed over Mount Fuji's peak.
The railgun shots we dodged dug up the side of Mount Fuji. Amidst the cloud of dust and debris, Mitsuki issued orders.
"Begin the attack on Yggdrasil's main body! If the main body is like a CPU, damaging it ought to lower Yggdrasil's computation power. This might be able to dampen its unrestricted growth and regeneration."
"Understood!"
In charge of attacking, Iris and Lisa responded.
Kili also went "got it" and went up to the front with a fearless smile.
Mitsuki raised Brionac. Holding onto Mitsuki's waist with her right arm, Iris raised her left hand.
"Come, come, fragments of time—"
Iris murmured like praying then generated a red glow in her hand immediately. The words she uttered served as an incantation to focus her mind. She had apparently made changes in order to use Catastrophe.
"—Caduceus Catastrophe!"
With a shout, the red glow turned into the shape of a staff. At first glance, it seemed to be a fictional armament of a different color, but most likely, no dark matter had been used.
It was definitely what Iris had used at Midgard last time, a staff formed from concentrating the light of Catastrophe.
"Iris-san, please attack after me!"
While Iris was preparing, Mitsuki aimed at Yggdrasil and fired the first shot.
"Terminating Arrow—Last Quark!"
Mitsuki fired an antimatter arrow that had eliminated several dragons to date.
But as though to block the arrow's advance, the branches spread above came down, entangling one another, forming a wall.
Mitsuki's arrow caused a giant explosion upon contact with that wall, destroying the branches. However, due to the distance, the antimatter explosion did not reach Yggdrasil's main body.
The branches forming the canopy came down to attack us from overhead. However, they were deflected by Firill and Ariella's barriers. But during this time, branches formed a new wall in front of Yggdrasil.
"Our attacks won't be able to reach the main body if it bolsters its defenses like this!"
Lisa raised Gungnir and shouted.
"Don't worry, Lisa-chan, I'll eliminate them all!"
Pointing the tip of her red staff towards Yggdrasil, Iris shouted acutely:
"Catastrophe, actualize!"
The red light of Catastrophe pierced the dawn sky.
An attack of red light, rivaling Basilisk's, devoured the wall of branches that Yggdrasil had weaved, instantly weathering it away into dust.
Without weakening, the light struck the railgun's discharge port directly.
The longer the duration of exposure, the more time was stolen. Slicing through Yggdrasil's gigantic tree trunk, Iris' beam pierced straight through.
The original location of the discharge port was turned into a giant hole.
"Pierce, flare!"
Seizing the chance, Lisa fired her specialty, the positron cannon, from the tip of her spear. Her attack made a direct hit on the top part of Yggdrasil—the base of the branches.
Severed from the main body, the branches instantly stopped moving and started to fall gradually towards the ground.
Passing through gaps in the falling branches, we increased our altitude and got within Yggdrasil's vicinity. In front of our eyes was a towering gigantic tree that was way too enormous.
"My turn."
Completely fearless, Kili raised her right hand towards the sky.
"—Laevateinn."
Extending a scarlet flash of light towards the sky, Kili swung that flash down like a sword.
The sword of flashing light left a trail on the morning clouds in the sky.
Chopping Yggdrasil's main body vertically, the light sliced into the center of the tree trunk, causing a large explosion. That shockwave caused Yggdrasil's trunk to split apart left and right.
"This time, I will strike the target."
Aiming at the crack in Yggdrasil caused by Kili's attack, Mitsuki released another antimatter arrow.
The pure white light of annihilation erupted from the inside of the trunk. The internally detonated explosion caused Yggdrasil's body to expand greatly. Losing balance, the body gradually collapsed under its own weight.
"It is almost time. Descend to the ground, scatter Ether Wind and attack Yggdrasil's mind using the anti-dragon armament."
Seeing Yggdrasil collapsing, Mitsuki gave orders.
Ren would no longer be able to fly once she passed all her dark matter to me. Furthermore, the anti-dragon armaments had to be secured on the ground for support, which necessitated landing.
"Onii-chan...!"
"Yes, let's start."
Ren held my hand tightly and I gripped back in return.
Unless I followed up on the attack, all we had accomplished was merely destroying Yggdrasil's body. Sooner or later, it would transfer its core to somewhere else.
Hence, before that could happen, we must drag on the contents to destroy it after obliterating the main body.
Finding a location with good visibility, we landed at a lakeside near Yggdrasil.
Everyone scattered to protect Ren and me. Helped by Tia who was in charge of preventing Yggdrasil's interference, I generated dark matter.
"Fictional armament—Siegfried."
I created the fictional armament shaped like an ornamental gun.
Then Ren placed her hand on Siegfried.
"I will only think about you, Onii-chan, and you will only think about me. That way, I'll definitely be able to give all of it to you."
"—Got it."
While I nodded in response, Ren's dark matter poured in.
It was a massive amount that I had never succeeded in controlling before.
However, my fictional armament expanded in volume in a stable manner without its shape going into disarray.
By thinking of each other strongly, we caused our dark matter to merge without problems.
It felt like Ren's mind was naturally permeating into mine.
My fictional armament grew to several dozens of meters in size within the blink of an eye.
Ordinary matter of that size would be almost impossible to balance or support. But the dark matter forming fictional armaments had the property of responding to thoughts and had no weight.
Consequently, I could support it with no effort, simply by thinking silently in my mind, the enlarged Siegfried remained in midair. Thanks to the electromagnetic barrier Tia deployed for us, the dark matter would not get stolen.
Responding to my will, Siegfried pointed its muzzle towards Yggdrasil.
While aiming, I compressed the dark matter pouring in from Ren inside the fictional armament.
"Onii-chan, just a bit more."
"...Got it."
I focused my mind, not letting the fictional armament collapse.
The fictional armament showed a hint of red color. Perhaps this was the color of Ren's thoughts.
"—This is everything."
Then Ren's dark matter was all poured into my fictional armament.
I turned all that dark matter into a single bullet.
Transmuted into golden particles that caused souls to materialize—
"Ether Bullet!!"
The fictional armament vanished the moment the bullet was shot.
The golden bullet, with everything of Ren's and mine poured in, shot high into the sky. Giving off intense brightness, it then exploded.
Instantly, the sky's color turned from pale blue to a dazzling golden.
Glittering brightly, the radiant particles drifted down from the sky.
It was finer than snow—Like golden diamond dust.
Descending from the sky, the Ether Wind gradually covered Yggdrasil's collapsing main body.
"How is it...?"
I observed the situation with bated breath.
If Director Miyazawa's predictions were true, then Yggdrasil's mind ought to manifest.
Amidst the drifting brightness, an outline gradually surfaced.
A scene just as hoped, but—
"This is... impossible."
Ariella muttered blankly.
The others gasped in surprise.
I did not make a sound, simply shocked by the sight before my eyes—
Yggdrasil's soul was gradually materializing as though flooding out of its collapsed body.
It was an outline of a giant tree, whose branches extended to the other side of the horizon, completely blotting the sky.
Its size was not merely 5000 meters, but much more gigantic.
Seeing its outline cut off unnaturally, I could tell that what the Ether Wind caused to manifest was merely a small portion of the whole.
This gigantic soul, how do we destroy it?
Only then did I realize we were too naive.
Yggdrasil's true nature was a network built from all the plants in the world. On further thought, it would not be strange even if its soul was on the scale of the Earth.
Just as all members of Brynhildr Class were stunned. Kili quietly looked up at Yggdrasil and turned towards me.
"Yuu? Aren't you going to fight? You're destroying that thing, right?"
"—!"
Her words prompted me to regain my senses.
Indeed... By this point, there was no choice but to do it. This was surely Yggdrasil's core without a doubt.
No matter how despaired, for the sake of everyone who had brought me here, I must not give up!
"—Ren, I'm going to borrow dark matter from you again, to construct an anti-dragon armament this time."
"Mm!"
Ren's eyes blazed with fighting spirit. She gripped my right hand firmly.
"Anti-dragon armament Marduk—Psionic multi-barreled cannon, Noah!"
I transmuted the dark matter flowing from Ren into a pre-civilization weapon.
Performing transmutation using blueprints in the mind was much easier than making a fictional armament.
A double-barreled turret appeared on a rotating artillery platform. With a design of glowing lines carved on its surface, the multi-barreled cannon was linked to my consciousness, aimed at Yggdrasil.
As a weapon that amplified and shot out the gunner's thoughts, Noah was effective against spirit bodies which did not interact with ordinary matter. This was already proven during the battle against Hraesvelgr.
—I will defeat you. I won't become your possession!
"Fire!"
Turning strong willpower into energy, Noah's multi-barreled turret fired two shells.
The shells struck the materialized spirit body, causing golden particles to fly into the air.
However, Yggdrasil's spirit body was far too humongous. These tiny shells did not produce much trace of destruction.
"—Fire! Fire! Fire!"
Even so, I still fired relentlessly.
But the more I repeated, the more I realized that my attacks were equivalent to a toy gun against Yggdrasil's spirit body whose size was extraordinary.
Even if I were to shoot dozens, thousands of times, I did not think I would succeed in destroying it.
My consciousness gradually grew hazy because the more I shot, the more mental energy was consumed. Even if I increased the number of turrets like during the battle against Hraesvelgr, it was pointless because my mind's energy was limited as the source.
"Fire—Huff, huff, huff..."
After who knew how many shots had been fired, I breathed heavily. My vision was blurred from the sweat entering my eyes. I could see Yggdrasil's spirit body standing upright, completely unshaken.
"Damn... it..."
There was no time left.
The Ether Wind scattered earlier was fading bit by bit.
"Onii-chan..."
Ren looked up at me with worry.
"I'm fine... I can still shoot."
I feigned vitality and forced myself to answer, then glared at Yggdrasil's spirit body that had appeared due to the golden particles.
I must endure... As the only one capable of attacking spirit bodies, I could not rely on the others.
I had relied so much on them beforehand, so I must accomplish this—
But my knees gave way.
My body was about to fall over forwards.
I slowly approached the ground... But stopped just before my face smashed the ground.
"Huh...?"
I came to my senses only to find Mitsuki, Iris and Tia's face before me.
"Nii-san, are you okay!?"
"Mononobe!"
"Yuu!"
The three voices sustained my consciousness that was about to be cut off.
"—Thank you all."
I thanked them and got up, but this time, I fell backwards.
However, warm hands caught me this time too.
"Goodness gracious, get a grip on yourself and stand properly."
"Do your best, Mononobe-kun."
"Mononobe-kun, hang in there."
Lisa, Firill and Ariella supported my body from behind.
"Sorry. Thanks."
I thanked them. Standing in the distance all alone, Kili asked me:
"Yuu, are you at your limit?"
"No... Not yet. I feel power surging from within."
This was not pretense. I really did feel I could continue to fight fiercely.
My heart felt very warm and it seemed like the mental energy I had depleted had recovered a little.
However, this was surely just my own wishful thinking.
Thoughts or mental energy could not be transferred to others like dark matter.
—When this thought crossed my mind, a question occurred to me.
Really... Is that true?
Who decided that mental energy could not be transmitted? When was it proven?
Through training with Ren, I found out that dark matter from other people consisted of fragments of the mind—fragments of thoughts and feelings.
The transfer of dark matter was equivalent to sending your thoughts to someone. To sustain the psionic multi-barreled cannon, Ren's dark matter continued to flow.
Was dark matter really the only thing Ren was giving me?
Those hands, tightly held together, supporting my heart, perhaps that kind of power would—
"Everyone, can I ask you for a favor?"
I asked the girls.
"What is it? I am willing to do anything in my power for you, Nii-san!"
Mitsuki instantly answered and the others urged me to tell them.
"I hope you will transmit your thoughts to me using the same principles as dark matter transfer."
I did not know if this would actually pass mental energy over. Even if it could, it would probably serve as merely psychological consolation.
But in order to fight to the very end, I sought everyone's power.
"Thoughts...?"
Iris widened her eyes, cocking her head in puzzlement.
"Yes, lend me your thoughts... the power of your heart and soul."
"—I understand. Just thoughts and feelings, isn't that right?"
Lisa nodded, applying force through her hand that was supporting my back.
"Mononobe-kun... I will think of you as strongly as I can."
Gripping my shoulder firmly, Firill spoke.
"I will cheer for you, Mononobe-kun."
Ariella said while touching my back.
My heart began to warm up. Everyone's thoughts were making me happy. My mind gradually felt satisfied.
Was this mental energy flowing in? Or simply the effect of receiving encouragement? I did not know actually.
But my originally sapped strength surged again, this was the truth.
I slowly took the power received from everyone and poured it into Noah. The lines carved all over the multi-barreled cannon began to glow with dazzling light.
"Tia is always always thinking of Yuu!"
"Nii-san, please accept my thoughts!"
Tia and Mitsuki pressed their hands on my chest, praying strongly.
Then Iris placed her hands on top of theirs.
"Mononobe—"
Iris simply called my name and smiled faintly.
But I could feel it. I could feel Iris' thoughts. I could feel intense feelings that made my chest hot.
Not only Iris but Tia and Mitsuki's emotions and words were giving me power.
The multi-barreled cannon, which converted mental energy into shells, rumbled, giving off light that shone all around.
"Onii-chan...... Don't lose!"
Gripping my right hand tightly, Ren cried out as hard as she could.
Ren's thought flowed into me together with her dark matter.
I could feel the unprecedented power of thoughts, dense and fierce, gradually growing stronger inside the anti-dragon armament.
Everything was poured into this one attack.
Let me fire the thoughts and feelings of insignificant humans towards Yggdrasil.
Let it know that we are living with such fiery emotions in our hearts.
"We're doing it, everyone."
"Yes!"
The girls responded to my call.
Then in unison, we fired our thoughts.
"FIRE!"
An intense glow expanded from the two muzzles, shooting at the sky. While firing, the psionic multi-barreled cannon exploded from within and collapsed.
The two balls of light melded together, forming a gigantic shell, striking Yggdrasil's spirit body.
Immediately exploding with blinding light, golden particles then scattered all over the sky.
The atmosphere shook slightly. The outline of Yggdrasil composed of Ether Wind shook for an instant.
Once the particles scattered and disappeared in the air, I could see a massive hole opened up in the center of Yggdrasil's spirit body.
However, the spirit body showed no signs of overall collapse.
"Damn it! This didn't work either..."
I said with frustration.
"Onii-chan... One more time."
Ren pulled my hand. She did not show any signs of giving up in her expression.
"—Yeah, until it's destroyed, we'll shoot no matter how many times it takes."
I nodded and prepared to construct the anti-dragon armament again, but Kili stopped me.
"No, this is good enough."
Kili approached me and smiled with satisfaction.
"Enough...? Yggdrasil's core consciousness isn't destroyed though."
"But damage has been inflicted, so next is your job—Tia."
Kili patted Tia, who had been lending me power, on the shoulder and said to her.
"Tia's job?"
Tia widened her eyes and stared at Kili.
"You should be able to hear it, right? Yggdrasil's screaming."
"...Yeah, but it's a mess. Can't hear what it's saying."
"That is evidence that the core's functionality is damaged. Given now, Tia, you'll surely prevail over Yggdrasil."
Kili grinned and continued.
"Your pair of horns is not simply for defending against Yggdrasil's interference. It is a weapon existing for the sake of devouring Yggdrasil, a power to enable you to become a dragon."
"The horns are a weapon... Become a dragon—"
Tia touched the horns on her head, apparently thinking of something.
"Against Yggdrasil that's trying to take Yuu's place, just do the same thing to it. Tia, you have that power."
"—Yeah!"
Tia nodded. Looking like she understood what she must do, she constructed her wing-shaped fictional armament on her back.
"Hey Tia!"
Before I could stop her, Tia had already flown into the sky, heading for Yggdrasil.
"Kili, what are you planning to have Tia do!?"
I glared at Kili and asked her what was going on.
"I simply presented a choice. Everything is Tia's own decision. Don't belittle her resolve."
Glared back by her with such intense emotions, I could not help but gasp.
"Mind your own business and quietly watch Tia's battle."
Kili spoke in a sharp tone of voice to stop Lisa and the others from chasing after Tia.
"You will soon know what Tia is about to do."
Staring at Tia in flight, Kili spoke quietly.
Tia arrived at Yggdrasil's spirit body then jumped into the hole I had punctured.
Several seconds later, blindingly bright lightning erupted with Yggdrasil as the center.
Flying through the air where golden particles drifted, Tia Lightning recalled the first time she met him—the time when she encountered Mononobe Yuu.
Back then, Tia did not quite understand much about herself.
Her parents called her human but demanded her to create gemstones through transmutation.
Later on, Tia and her parents were captured by an armed gang. This time, she was exploited as a D with the power to generate dark matter.
Hence, Tia had asked him—Mononobe Yuu who had rescued her from that armed gang—What am I?
Then with broken speech, he replied in Tia's mother tongue:
'You are a—cute, girl.'
It was a very gentle answer.
Tia wanted to become like that, hoped for herself to become like that, it was the answer Tia desired too.
Tia had always kept those words in her heart.
Meeting Kili, raised to become a dragon, selected by Basilisk—Tia had abandoned that dream once... But after reuniting with him and rescued by Lisa and the others, Tia made a decision as a result.
Tia would live together with Lisa and the others as humans.
To become the cutest girl of all in Mononobe Yuu's eyes—to become his wife.
Then like how he had protected her, she would protect him too.
"Tia will save Yuu!"
Tia generated wind from her fictional armament, a pair of red dragon wings, and charged into the interior of Yggdrasil's spirit body.
Her surroundings were covered by golden particles, so bright that her eyes could almost see nothing. Tia heard Yggdrasil's cries in her mind.
'Thought, flaw—collapse, reject—reject, reject, reject, repair, prioritize—'
Not just a voice. Through her horns, Tia could sense intangible feelings.
"—It's afraid."
Tia murmured.
Yggdrasil was afraid. Afraid of its consciousness disappearing, afraid of losing its existence, afraid of eath—Extremely extremely frightened.
'Neun—needed, must have—uncertain, ninth authority, one and only—most suitable, survival strategy—'
And it wanted—
To survive, it needed Mononobe Yuu.
Tia could sense this concretely.
Tia did not know what it was afraid of. Yggdrasil's thoughts were fragmented, incomprehensible.
However—
"You're not having him!"
Tia declared to Yggdrasil in no uncertain terms.
"Because Yuu will become Tia's husband!!"
Tia poured all her thoughts into dark matter, transmuting it into electricity then released it.
Tia's consciousness spread as an electromagnetic field, expanding inside of Yggdrasil.
Attacked and damaged by Noah, Yggdrasil's core system had encountered a bug, allowing Tia's consciousness to invade.
Hacking into Yggdrasil, this was precisely the true function of the pair of horns given to Tia.
"...!"
Intense pain struck her head, causing Tia to frown. Yggdrasil was resisting, it was struggling, trying to evict Tia's consciousness that was invading in the form of electrical signals.
"Tia won't lose... This time, Tia will protect Yuu!!"
Using willpower as fangs, turning emotions into claws, Tia bit and ripped apart Yggdrasil's consciousness.
Tia's thoughts were endlessly amplified by the electrical energy obtained through the transmutation of dark matter, gradually conquering the core system.
The golden particles shrouding the surroundings shook. It was a sign that Yggdrasil's spirit body was starting to change.
'—Reject, reject, reject, unacceptable, overload, unacceptable—destroy, reject, reject—!'
Yggdrasil resisted desperately but the CPU had been destroyed physically, the mind was damaged, and right now, its computational power had dropped to its limit.
Conversely, after devouring Yggdrasil's consciousness, Tia's thoughts had acquired overwhelming processing power.
But due to excessive expansion of her ego, her original self turned fuzzy. Having obtained processing power that was originally impossible for humans to have, Tia's mind could not keep up with her thoughts.
"Tia is... what?"
Amidst her expanding ego, her consciousness was wavering.
But his words, carved deeply in her heart, kept Tia's consciousness together.
—You are a—cute, girl.
Tia gritted her teeth and used her dark matter to the limit to use her thoughts to rewrite everything.
"That's right... Tia... Tia will become Yuu's wife!!"
Then her will raced along the network formed from plants, exploring Yggdrasil's true nature.
Then she understood. The power to control electricity was merely one part of Yggdrasil's true nature.
The name of the authority was: Akashic Record.
There, Tia caught a glimpse of everything.
Composed of golden particles, Yggdrasil's mind twisted and changed in shape.
The gigantic body, never collapsing no matter how many times Noah attacked, changed in form as though melting.
"Tia... What did she do?"
I looked in surprise but I was soon struck by even greater shock.
Shaking, gradually fading away, the Ether Wind proceeded to trace out a certain outline.
Instead of a giant tree, it was the silhouette of a young girl.
"Tia-chan...?"
Iris cried out in surprise.
Indeed—The golden particles were undoubtedly showing the figure of Tia Lightning.
"Looks like it's a success. Tia has already taken control of Yggdrasil's core."
Kili smiled happily and explained to us.
"What... Control of the core?"
Since it was too shocking, I could only repeat like a parrot.
"Yes, capable of outputting thoughts as electrical signals, right now, Tia can electrically interfere with senses, in other words, hack into Yggdrasil then tamper with the core, forcing the system to recognize her as the new core."
Kili replied so nonchalantly, but after seeing the Ether Wind fade away, she smiled.
"From the start, I raised Tia intending to have her devour Yggdrasil. But back then, I had no idea that Yggdrasil was such a terrifying monster. If we had challenged it normally, I think we would've failed already. It's all thanks to you inflicting damage to the core, Yuu, that we succeeded on this occasion."
The golden particles scattered amidst the sky's morning glow.
The particles showing Tia's image also disappeared gradually.
Visible under the particles was Yggdrasil's collapsed remains and a girl with a pair of radiant wings on her back.
Looking up at the young girl flying back to our side, Kili said proudly:
"Look, Yuu, this is the new dragon I raised—Tia Lightning Yggdrasil."
Tia Lightning thought back to what Kili Surtr Muspelheim had told her at the Castle of Mirrors.
"As things stand, Tia, Yggdrasil cannot be defeated no matter what. But if you give up your human identity, there might be a path to hope."
"Eh...?"
Tia stared blankly at Kili.
The hall all covered with mirrors gave an illusion of infinite space. At the same time, it also produced countless reflections of Tia and Kili.
An uncountable number of virtual images—Facing the black-haired girl was the girl with two red horns on her head in great unease.
"I originally planned to raise you as the trump card for taking down Yggdrasil. Your horns are also an organ existing for the sake of opposing Yggdrasil."
"These..."
Putting her hands on her head, Tia touched her two red horns.
"Indeed, this is an organ connected directly to the brain, which is why I can't put it on myself. Manipulating your own brain will mess up your concentration in the process, causing the control of biogenic transmutation to fail."
"Then... If Tia works hard, Yggdrasil can be defeated?"
Tia asked timidly but Kili shook her head.
"No, I haven't finished with your treatment, so those horns cannot function as intended yet. But if you wish, I could perform the final treatment for you."
Staring into Tia's eyes, Kili made this proposal.
"Then like this... Tia will be able to help Yuu and the others?"
"If all goes well. After all, I can't guarantee success since this is the first time, but if your horns function as planned, Yuu and the others have a shot at victory. However—"
Kili paused and narrowed her eyes.
"—The moment Yggdrasil is defeated, you will surely become a dragon transcending the boundaries of Ds and humans."
"...!"
Tia gasped and took a step back.
"Don't worry, I won't force you, so no need to be afraid. I'm no longer a puppet controlled by Mother. I will freely decide my 'way of living' according to my own will, so please make a choice according to your own wishes."
Kili's expression turned gentle and she smiled at Tia.
"Kili..."
It was a gentle smile that Tia had never seen on Kili's face.
"Yuu said before that how one lives their life is more important than what they are. What matters is not the identity of your existence, but what you want to do."
In the middle of this predicament with Yggdrasil's branches flooding towards us, I was stunned on the spot with all eyes on me.
My secret had been revealed.
The fact that Yggdrasil was stealing my body had been exposed.
Finally, she still ended up finding out. Clearly when Mitsuki was the one person I did not want to know this secret.
"Mononobe-kun, tell me the details."
"I want to hear your explanation."
Firill and Ariella approached to question me.
"Yuu, tell Tia the truth..."
Tia stared at me with determination, refusing to back down by a single step.
"I'm interested in the details too."
Kili urged me to explain with her gaze.
By this point, I could not cover things up anymore.
Gritting my teeth, I searched for an answer to give them, but—
"Mononobe Yuu, clearly the only choice is to tell them. The weapons you used so far to defeat dragons were created based on data provided by Yggdrasil. The price you paid is that your body is now about to be stolen."
Lisa's fictional armament fired a flash of light, attacking the branches above while she spoke to me.
However, what she said felt strange to me.
"Huh...?"
Hearing her say that, Iris stared wide-eyed from the side.
The price paid under the deal with Yggdrasil was the loss of my memories, while taking over my body was the trap it had laid. These two were a bit different in meaning.
When my thoughts reached this point, I noticed something. When Tia overheard my conversation with Lisa, the subject of memory loss was not mentioned.
Then at least the worst situation—that I was not the "Mononobe Yuu" whom Mitsuki knew—Perhaps this one fact could still remain hidden to the very end.
...Thank you, Lisa.
While feeling grateful for Lisa's quick thinking, I started to explain to Mitsuki and the others.
"Just as Lisa said, I secretly made a deal with Yggdrasil to defeat dragons. But there was apparently something similar to a computer virus in the data that was sent, so gradually—and right now—I'm being invaded by Yggdrasil."
Omitting the memory part, I revealed the truth.
"To defeat dragons...? Could it be that three years ago, Nii-san, you—"
Mitsuki murmured blankly.
Three years ago, to protect my hometown, I used a power, which was normally impossible, to repel Hekatonkheir. This was done exactly by relying on anti-dragon armaments created from the weapons data obtained from Yggdrasil.
Smart as she was, Mitsuki seemed to recall that immediately.
"Yeah, the fight against Hekatonkheir three years ago was the first time."
I nodded in response to Mitsuki, despite knowing that Mitsuki would feel heavily guilty as soon as I confirmed it.
However, this was much better than telling her "the price was memories."
As long as Yggdrasil was neutralized, its invasion of me would presumably stop, but there was no guarantee my memories would recover.
When it was impossible to recover the real "Mononobe Yuu"—I did not want to bring despair to Mitsuki.
"Mononobe-kun... Why did you hide this? If the weapons for defeating dragons is the reason, then you must have made a deal again back when I was in a crisis, right?"
Firill glared at me angrily.
"...Sorry, because I didn't want you to feel responsible or in debt. Also, I only found out recently I was being controlled. I never expected things to turn out this way."
I bowed my head and apologized to Firill.
Seeing me like that, Ariella scolded:
"I understand how you feel, Mononobe-kun, but it pisses me off that we're the only ones kept in the dark. From the way it looks, Iris and Ren also knew in addition to Lisa, right?"
Iris looked down in shame when Ariella glanced at her, but Ren met her gaze and pointed her finger in the air.
"Mm."
I took a closer look. Because fewer people were attacking, the branches were gradually closing in.
"—Meaning it's not the time for arguing? Can't be helped, I'll complain properly later."
Ariella returned to attack after glaring at me.
"Me too... I have things to say but I'll hold back for now."
Firill turned her back to me and started attacking the branches again.
"—As thanks for letting me hear something interesting, I'll help out a bit."
With a wave of her hand, Kili incinerated branches with a red beam of scorching heat.
But in this situation, Mitsuki and Tia did not take their gazes off my face.
I saw Mitsuki biting her lower lip, shoulders trembling, a tear sliding down her cheek.
"M-Mitsuki—Don't cry. It's really my fault, I'm sorry—"
Even I was surprised at how shaken I was inside. I kept apologizing to her. To me who had lost all memories beyond three years ago, she should not be someone "special"... But my heart was shaken to a ridiculous degree.
"...Nii-san, you need not apologize. I am crying because I am too useless... This fills me with chagrin... So do not worry about me."
Mitsuki spoke hoarsely and brusquely wiped her tears away with her hand.
"Putting that aside, please allow me to confirm one fact. Is what you said just now everything?"
"Eh..."
My heart pounded like crazy.
"I knew long ago that you were hiding things from me, Nii-san, but I also understood you were hiding desperately... So I deliberately refrained from asking, but this incident has filled me with extreme regret. So this time, I will muster my courage to ask you, Nii-san, are you still hiding things from me?"
Mitsuki asked me with conviction.
I thought I had concealed things well, but now I knew I was totally seen through.
More than anyone else, Mitsuki knew this person of "Mononobe Yuu." She knew everything about me that my current self had forgotten. In front of someone like that, of course hiding would not work.
"...Yes."
I nodded to confirm Mitsuki's question, but I continued:
"But I can't tell you, Mitsuki."
I prepared myself and asserted clearly.
"Why?"
"I still can't say it yet."
I shook my head and stared into Mitsuki's eyes that were red from crying.
"Then when can you say it?"
"—Once I've retrieved everything."
I gave this answer because I could not think of another way of saying it.
"Even if I ask you what you mean by that, you will not answer, right?"
Mitsuki smiled wryly with feelings of resignation.
"...Sorry."
"Very well—Because I know how stubborn you are, Nii-san, I will not force the matter at this time. However, one final matter, please tell me—Tia-san said that Yggdrasil must be defeated now. Is that true?"
Mitsuki's expression tensed. She asked me in a tone of suppressed emotion:
"...It's true that Yggdrasil's interference in me has strengthened, but I won't get controlled by it immediately, so there's still time. We should retreat temporarily."
To be honest, I had a feeling that the final time limit was not far away, but I answered this way to reassure Mitsuki. Because right now, we were totally out of options.
I was admittedly happy that Tia said she would protect me, but right now, we should retreat and request reinforcements from Midgard. With a larger force, it might be possible to handle the branches' rate of growth.
"I understand. Indeed, as the captain of the Dragon Subjugation Squad, there is no alternative as a decision. Well then—"
Mitsuki paused halfway then turned to face Shinomiya-sensei.
"Shinomiya-sensei, forgive my willfulness, but I, Mononobe Mitsuki, hereby relinquish my duties as captain of the Dragon Subjugation Squad."
"What are you suddenly..."
Shinomiya-sensei was shocked.
The others, still attacking branches, also stared in Mitsuki in surprise.
"Mitsuki-chan...?"
Troubled, Iris called her name, tilting her head in puzzlement.
"Mitsuki..."
Tia also showed doubt on her face but I could also see her trying to figure things out.
But ignoring everyone's reactions, Mitsuki turned to face me.
"Starting now, I will only fight as your younger sister to protect you, Nii-san. I will absolutely not retreat."
"H-Hey—I said there's still time, right?"
"Nii-san, do you think lying can deceive me?"
As though having come to a realization, Mitsuki showed a refreshing smile while glaring at Yggdrasil's branches extending from the western sky.
"Hold on, what do think think can still be done in this situation? If there's a solution, I wouldn't call for a retreat."
The way I saw it, Mitsuki was going to attack recklessly without a plan. I made haste to stop her.
"Indeed, given the current situation, marching forward while keeping sufficient distance from the interference range will be impossible. However, much can be done as long as one disregards one's safety. Such notions would disqualify a commander... But right now, I am merely a younger sister, nothing more."
Mitsuki smiled as though telling a joke and continued:
"By eliminating branches in the minimum range ahead and flying at high speed, it might be possible to advance."
"What...? But if you get caught in Yggdrasil's interference range, even if just a little, you'll crash immediately, right? It's too dangerous!"
I instantly yelled in objection.
"—I know, which is why I intend to go alone. I will find a way to reach a spot where I can aim at Yggdrasil directly, to destroy the base of the branches. That way, I should be able to buy quite a lot of time before it grows again. Nii-san, you and the others will use that window to attack."
Mitsuki's expression showed that she was completely prepared already.
"Don't do something stupid like that—"
I reached out, trying to stop Mitsuki, but she was surrounded by a layer of wind, deflecting my hand.
Everyone tried to call out and stop her with frantic expressions.
But before anyone could make a sound, she acted even faster.
"Wait!"
Mitsuki hovered into the air, but Tia crashed into her, wrapped in her own layer of wind.
"Kyah!?"
Entangled together, the two girls fell to the ground.
"Tia-san, let go of me!"
Mitsuki tried to pull off Tia who was hugging her waist but Tia resisted desperately and yelled:
"Don't do that, Mitsuki! Leave it to Tia! If it's Tia, it will definitely succeed!"
"Huh...?"
Hearing what Tia said, Mitsuki stopped.
"Sorry, Tia should have said this earlier, but Tia finds the current life so happy... Don't want any change... So Tia could not gather enough courage. But Tia has decided now."
Tia separated from Mitsuki who had stopped resisting, then looked at Kili.
Originally helping out with eliminating branches, Kili stopped and faced Tia at this time.
"Is that right? Tia, you will be choosing your way of living."
Kili spoke gently to Tia.
I did not know what was going on, but my heart was in turmoil.
Tia nodded and said with a voice of determination:
"Please, Kili, give Tia the power to fight Yggdrasil."
"Got it, then I'll perform the final treatment for you."
Kili slowly approached Tia.
"Hey, what treatment? What are you planning to do!?"
Unable to grasp the situation, I yelled acutely at Kili.
"—I will make Tia's horns complete."
Kili placed her palm on the pair of horns on Tia's head and gave me a brief answer.
"Make her horns complete... What on earth is—"
"Tia is the child I raised to become the trump card against Yggdrasil. These horns were created as an organ for opposing Yggdrasil. Although the horns currently don't function, so long as Tia wishes, I can make these horns complete. This was what I proposed to her at the amusement park."
Staring at Tia's horns, Kili quietly explained.
So that was what they talked about in the Castle of Mirrors that time—
"...Tia has been brooding the whole time after returning from the amusement park, like she was in a dilemma... afraid of something. Is that final treatment something frightening to Tia?"
I stared at Kili and questioned her in a fierce tone of voice.
"Yes, I don't know what will happen if it fails. Even if it succeeds, Tia will become an existence transcending the boundaries of what it means to be a D. Based on Midgard's definitions, she might end up categorized as a dragon."
Hearing Kili's words, Iris' shoulders shuddered.
As a D who had transcended boundaries, Iris must have felt greatly shaken inside after listening to Kili.
"I won't let Tia do something so dangerous!"
"That's not for you to decide."
Just as I tried to take a step forward, a small explosion detonated in front of me.
"!?"
I guarded my face with my hand and jumped back reflexively. The searing pain on my skin forced me to frown.
"Don't get in the way, Yuu. Even you have no right to stop Tia from choosing her own path."
Exuding off intense killing intent, Kili restrained me from taking action.
The surrounding temperature rose. Sweat was seeping out of my forehead and neck. She must have deployed Muspelheim.
What should I do...? Stopping them would require the determination to murder Kili.
Just as I hesitated, Tia smiled at me.
"Don't worry. Because no matter what Tia becomes, Tia will be still the one who loves Yuu most—Yuu's wife."
Then the dark matter generated in Kili's hand melded with Tia's horns as though getting sucked in.
"—!!"
The two horns shone with dazzling light while Tia emitted a deafening scream.
Blinding light and an extended scream.
"Tia!"
Ignoring Kili's deployed Muspelheim, I dashed towards Tia.
The final treatment probably ended in an instant—Kili did not stop me. After she put down her raised hand, Tia immediately collapsed on her knees.
As though sliding, I caught Tia's petite body, feeble and drained of strength.
"Stay with me! Tia!"
I called to her but Tia seemed to have lost consciousness. No reaction. Her two red horns also showed no change in appearance.
"Tia-chan, are you okay!?"
"Tia-san!"
Iris and Mitsuki rushed forward from behind, peering at Tia's face.
Unable to leave their positions from eliminating branches, Lisa and the others looked in our direction with paled faces.
I looked up and glared at Kili.
"What happened to Tia? Did it—fail?"
"Can't tell until Tia wakes up. The completed horns have connected to Tia's brain, so as long as she is able to withstand the strain, she'll surely—"
Just as Kili spoke in a praying tone of voice, Tia stirred.
"Mm..."
A faint sound came Tia's pink lips. A spark of lightning flashed and popped near her red horns.
"Tia can hear..."
Tia spoke hoarsely while opening her eyes slightly.
"Thank goodness, you woke up."
I breathed a sigh of relief, only to see Tia staring at me.
"Tia can hear a cold voice calling Neun... Neun... Is this the voice of Yggdrasil that's troubling Yuu?"
"What...? You can hear it too, Tia?"
I asked in surprise.
Just as Tia said, Yggdrasil's voice was still sounding in my mind right now.
"Yes... So this is Yggdrasil... Yuu's enemy."
Tia spoke as though in the middle of a dream and stood up.
"Tia?"
I noticed Tia acting a bit strange and called to her but she focused her gaze westward towards Yggdrasil instead of answering. The electrical sparks scattering over Tia's head in the horns' surroundings gradually increased.
"...Stop making Yuu suffer, be quiet!!"
The instant Tia yelled, electricity exploded nearby.
"What!?"
Boom, Shinomiya-sensei's laptop exploded. The surroundings suddenly felt quiet.
"Yggdrasil's voice... disappeared?"
I muttered blankly. Yggdrasil's voice was originally loud enough to feel noisy, but now, no matter how I much I focused my mind in order to listen, I could not sense the voice anymore. The sense of dissonance in my left arm also disappeared.
"Looks like it succeeded."
While everyone was feeling troubled, Kili was the only one to show a contented look.
"What did Tia do?"
I demanded an explanation from Kili.
"—What Tia has constructed is an electromagnetic barrier that could probably block out Yggdrasil's interference completely. And if my predictions are correct, Yggdrasil is currently unable to steal Tia's dark matter. Just by maintaining this barrier, your side will be able to enter Yggdrasil's interference range."
"What... Tia is now capable of that kind of thing?"
I gasped and asked.
"Yes. Speaking of which, the reason why Yggdrasil can steal dark matter is because electrical signals simulating thoughts will have more interference strength than weak mental waves. That's why I've given Tia a renewed organ capable of outputting thoughts as electrical signals."
"Namely... those horns?"
I looked at Tia's horns, surrounded by glowing electricity.
"Also, Tia has a habit of subconsciously transmuting dark matter into electrical currents. When the dark matter is transmuted emotionally, it becomes equivalent to thoughts encoded into electrical signals. This further strengthens Tia's interference strength, repelling Yggdrasil's interference. This is the truth behind the electromagnetic barrier."
Thinking back, Tia really did have a habit of generating electrical currents when emotional. That was probably why Kili had chosen Tia.
After listening to that, Tia held her head and asked Kili:
"So... If it's Tia right now, Tia can protect Yuu and the others?"
"That's right. As long as you think intensely and generate dark matter persistently, the electromagnetic barrier will be sustained. As long as they stay inside the barrier, the dark matter of Yuu and the others will be free from interference."
"Got it... Tia will work hard."
Tia nodded and moved her hand away from her head. I saw pearl-like sweat on her head.
It was probably causing her quite a lot of strain. Bestowed with an organ that was not inborn, it was only natural for her body to have a rejection reaction.
But Tia steadied her shaking body with her legs and spread the pair of red wings that was her fictional armament.
"Yuu—Everyone follow Tia. Tia will take everyone to Yggdrasil."
Tia spoke with unshakable determination.
Will you be okay? I could only swallow these words.
Because I quickly understood that it was a meaningless question. Asking it would be a waste of time.
I could see that she was not okay at all. She was clearly forcing herself.
In reaction to becoming like this—No, she had chosen to do this.
Simply for the sake of protecting me.
Lisa silently approached Tia and hugged her.
"—I know, then I will count on you, Tia-san. However, please focus on maintaining the barrier. I will fly and carry you."
"Thank you... Lisa."
Tia dispelled her fictional armament and held onto Lisa's waist.
"...I will carry Onii-chan."
Feeling someone pull my right hand, I turned my gaze to see Ren looking up at me.
Ren's cooperation with me was the key to the next part of the plan, so it was probably better that I traveled with her.
"Okay, I'm counting on you."
I held Ren's hand. Having confirmed the situation, Mitsuki walked over to Iris and took her hand.
"Then I will be responsible for Iris-san's transport. So this is it—Shinomiya-sensei, we are setting off."
Holding the wrecked laptop in her hand, Shinomiya-sensei was looking a bit lost. Then at this time, she smiled wryly and acknowledged.
"Okay... Looks like I can't provide support anymore, so I'm leaving the rest to you. Captain of the Dragon Subjugation Squad—Mononobe Mitsuki."
Shinomiya-sensei intentionally added the title when addressing Mitsuki.
Having just declared she would relinquish her duties, Mitsuki made a slightly embarrassed look before saluting with upright posture.
"Affirmative. I will fulfill my duties as the captain of the Dragon Subjugation Squad."
Gathered around Lisa, who was carrying Tia in her arms, we flew through the night sky.
Yggdrasil's branches were growing at a frightening rate in front of us.
Although it was impossible to measure the exact interference range, the area under the branches was most likely its territory.
We cautiously lowered our altitude and rushed into Yggdrasil's interference range.
—No change.
Having confirmed there was no interference in our fictional armaments or any signs of impedance to transmutation, we increased our altitude and flying speed. The sky glowed white faintly. Dawn seemed to be approaching.
Flying in the lead while carrying Iris in her arms was Mitsuki. Holding the rear was Ren, transporting me, with Kili flying by our side.
"How unexpected. I can't believe you came along, Kili."
Flying in the sky with Ren holding my hand, I spoke to Kili beside me.
"Let me enjoy the show to the very end since I'm already here. Of course, I won't just watch. I'll offer a helping hand and won't drag you down, so relax."
"I don't doubt your abilities, but I'll be watching you to see if you have any ulterior motives."
I declared to Kili that I refused to trust her.
"Fufu, I don't mind. That means you'll have your eyes focused on me."
Kili smiled confidently.
"...!"
Her smile was inexplicably dazzling and stunning, rendering me speechless for a moment. Sure enough, this girl was not easy to deal with.
"However, you should probably focus your attention on Yggdrasil rather than me. Once it realizes its interference over dark matter isn't working, it will surely take other measures."
Just as Kili reminded me to pay attention, Mitsuki yelled from the front:
"Heads up, Yggdrasil's branches are showing changes! Be careful, everyone!"
I hastily looked up to notice that we were already under a canopy made from Yggdrasil's branches.
These capillary-like branches blotted the sky, writhing in a sinister and spooky manner. Numerous branches, as sharp as spears, were attacking our position.
"All units deploy shields! We will break through by force!"
Mitsuki commanded in a sharp voice.
"Looks like it's my turn."
Kili grinned proudly and raised one hand to the sky.
"—Such flammable-looking branches won't even manage to enter my Muspelheim."
The approaching branches suddenly caught fire, burning into tiny particles of ash.
She had most likely deployed an invisible barrier of high temperature in the air.
Mitsuki and the girls also deployed barriers of wind, but all the branches were burnt to ash before reaching them.
Under the gradually brightening sky, the outlines of Mount Fuji's tall appearance and the towering Yggdrasil were gradually coming into view.
"Target confirmed! Once we pass over Mount Fuji, our distance to the target will be 10 kilometers or so—Sniping distance. Iris-san, show time for you!"
"Yeah!"
Iris nodded in response to Mitsuki.
"Once we pass Mount Fuji, Lisa-san, Iris-san and I shall attack the main body in full force while trying to get even closer. Firill-san and Ariella-san, continue to deploy shields. Nii-san and Ren-san will prepare to scatter Ether Wind after the main body is destroyed!"
"Yes!"
I answered and made eye contact with Ren, exchanging nods in acknowledgement.
"Huh? What about me?"
Without being called on, Kili asked, prompting Mitsuki to reply in a cold voice:
"If you wish to help, please participate in attacking."
"Oh dear, it feels like you're not expecting much of me?"
Kili grumbled with dissatisfaction.
Immediately, Iris, who was carried by Mitsuki, looked back and smiled cheerfully at Kili.
"It's not like that, Kili-chan, let's do our best together!"
"...Y-You're really good at getting others caught in your pace. Fine, whatever. Having created this chance for Tia, even without being told, I seriously intend to go on a rampage."
Kili spoke with violence in her eyes.
The snowtop of Mount Fuji was before us, but the branches suddenly stopped attacking.
Just as it seemed like Yggdrasil had given up on obstructing us with branches, Lisa yelled acutely.
"Look quickly! Yggdrasil's shape—"
Located on the far side, Yggdrasil's towering trunk was gradually expanding unnaturally in the middle.
Then bizarre and thick branches were forced out from the bulging portion.
The sun seemed to rise at last and the sky brightened all at once. Behind us, the sun's rays from the east were making us slightly dizzy.
"Everyone! Go down rapidly right now!"
Just at this moment, I heard Tia shout anxiously.
"Yggdrasil's target is Tia!"
Hearing Tia's urgent voice, everyone lowered their flying altitude without fully understanding what was going on.
In the next instant, a flash of blinding light rushed past us above.
"W-What was that!?"
Firill cried out in surprise.
"No idea, it seems like something flew out from Yggdrasil..."
Ariella had not figured out the situation either.
"Dodge quickly! It's aiming again!"
Tia yelled again.
"Descend further!"
Mitsuki instantly ordered us.
After we obeyed, another flash of light passed over us.
"That light... Its speed... The power of electrical interference—It might be an object shot at high-speed using electromagnetic induction."
Flying ahead, Mitsuki said in a stiff tone of voice.
"Isn't that a railgun!? Isn't it impossible to dodge if something like that is aiming at us!?"
Lisa yelled anxiously but Kili interjected confident after hearing her:
"—Don't worry. Tia noticed the attacks in advance, twice already, right? Tia, did you feel anything?"
Tia nodded lightly at Kili's question.
"Yes, there's a dangerous feeling."
"I knew it. Tia's horns are also quite sensitive towards external electromagnetic waves. Although it wasn't an ability by deliberate design, as long as we have Tia, we should be able to dodge."
After Kili said that, Tia made an alarmed expression and yelled:
"It's coming again!"
"All units dodge right!"
Mitsuki instantly commanded.
I could see a glowing ball shot out from the branches protruding from Yggdrasil's trunk.
Just as I was thinking that, a blinding light flashed past our left.
As Lisa said, it would be impossible to dodge visually.
But such a powerful attack could very well get me caught up in it too. Yggdrasil seemed quite shaken when harming me in Midgard. Although the reason was unknown, it looked like it wanted to obtain me intact.
Nevertheless, Yggdrasil seemed to be prioritizing the elimination of Tia over ensuring my safety. Perhaps that was how much of a threat it viewed Tia.
"It's not over!"
We listened to Tia's directions and steadily closed in on Yggdrasil while evading the railgun shots.
Finally, we passed over Mount Fuji's peak.
The railgun shots we dodged dug up the side of Mount Fuji. Amidst the cloud of dust and debris, Mitsuki issued orders.
"Begin the attack on Yggdrasil's main body! If the main body is like a CPU, damaging it ought to lower Yggdrasil's computation power. This might be able to dampen its unrestricted growth and regeneration."
"Understood!"
In charge of attacking, Iris and Lisa responded.
Kili also went "got it" and went up to the front with a fearless smile.
Mitsuki raised Brionac. Holding onto Mitsuki's waist with her right arm, Iris raised her left hand.
"Come, come, fragments of time—"
Iris murmured like praying then generated a red glow in her hand immediately. The words she uttered served as an incantation to focus her mind. She had apparently made changes in order to use Catastrophe.
"—Caduceus Catastrophe!"
With a shout, the red glow turned into the shape of a staff. At first glance, it seemed to be a fictional armament of a different color, but most likely, no dark matter had been used.
It was definitely what Iris had used at Midgard last time, a staff formed from concentrating the light of Catastrophe.
"Iris-san, please attack after me!"
While Iris was preparing, Mitsuki aimed at Yggdrasil and fired the first shot.
"Terminating Arrow—Last Quark!"
Mitsuki fired an antimatter arrow that had eliminated several dragons to date.
But as though to block the arrow's advance, the branches spread above came down, entangling one another, forming a wall.
Mitsuki's arrow caused a giant explosion upon contact with that wall, destroying the branches. However, due to the distance, the antimatter explosion did not reach Yggdrasil's main body.
The branches forming the canopy came down to attack us from overhead. However, they were deflected by Firill and Ariella's barriers. But during this time, branches formed a new wall in front of Yggdrasil.
"Our attacks won't be able to reach the main body if it bolsters its defenses like this!"
Lisa raised Gungnir and shouted.
"Don't worry, Lisa-chan, I'll eliminate them all!"
Pointing the tip of her red staff towards Yggdrasil, Iris shouted acutely:
"Catastrophe, actualize!"
The red light of Catastrophe pierced the dawn sky.
An attack of red light, rivaling Basilisk's, devoured the wall of branches that Yggdrasil had weaved, instantly weathering it away into dust.
Without weakening, the light struck the railgun's discharge port directly.
The longer the duration of exposure, the more time was stolen. Slicing through Yggdrasil's gigantic tree trunk, Iris' beam pierced straight through.
The original location of the discharge port was turned into a giant hole.
"Pierce, flare!"
Seizing the chance, Lisa fired her specialty, the positron cannon, from the tip of her spear. Her attack made a direct hit on the top part of Yggdrasil—the base of the branches.
Severed from the main body, the branches instantly stopped moving and started to fall gradually towards the ground.
Passing through gaps in the falling branches, we increased our altitude and got within Yggdrasil's vicinity. In front of our eyes was a towering gigantic tree that was way too enormous.
"My turn."
Completely fearless, Kili raised her right hand towards the sky.
"—Laevateinn."
Extending a scarlet flash of light towards the sky, Kili swung that flash down like a sword.
The sword of flashing light left a trail on the morning clouds in the sky.
Chopping Yggdrasil's main body vertically, the light sliced into the center of the tree trunk, causing a large explosion. That shockwave caused Yggdrasil's trunk to split apart left and right.
"This time, I will strike the target."
Aiming at the crack in Yggdrasil caused by Kili's attack, Mitsuki released another antimatter arrow.
The pure white light of annihilation erupted from the inside of the trunk. The internally detonated explosion caused Yggdrasil's body to expand greatly. Losing balance, the body gradually collapsed under its own weight.
"It is almost time. Descend to the ground, scatter Ether Wind and attack Yggdrasil's mind using the anti-dragon armament."
Seeing Yggdrasil collapsing, Mitsuki gave orders.
Ren would no longer be able to fly once she passed all her dark matter to me. Furthermore, the anti-dragon armaments had to be secured on the ground for support, which necessitated landing.
"Onii-chan...!"
"Yes, let's start."
Ren held my hand tightly and I gripped back in return.
Unless I followed up on the attack, all we had accomplished was merely destroying Yggdrasil's body. Sooner or later, it would transfer its core to somewhere else.
Hence, before that could happen, we must drag on the contents to destroy it after obliterating the main body.
Finding a location with good visibility, we landed at a lakeside near Yggdrasil.
Everyone scattered to protect Ren and me. Helped by Tia who was in charge of preventing Yggdrasil's interference, I generated dark matter.
"Fictional armament—Siegfried."
I created the fictional armament shaped like an ornamental gun.
Then Ren placed her hand on Siegfried.
"I will only think about you, Onii-chan, and you will only think about me. That way, I'll definitely be able to give all of it to you."
"—Got it."
While I nodded in response, Ren's dark matter poured in.
It was a massive amount that I had never succeeded in controlling before.
However, my fictional armament expanded in volume in a stable manner without its shape going into disarray.
By thinking of each other strongly, we caused our dark matter to merge without problems.
It felt like Ren's mind was naturally permeating into mine.
My fictional armament grew to several dozens of meters in size within the blink of an eye.
Ordinary matter of that size would be almost impossible to balance or support. But the dark matter forming fictional armaments had the property of responding to thoughts and had no weight.
Consequently, I could support it with no effort, simply by thinking silently in my mind, the enlarged Siegfried remained in midair. Thanks to the electromagnetic barrier Tia deployed for us, the dark matter would not get stolen.
Responding to my will, Siegfried pointed its muzzle towards Yggdrasil.
While aiming, I compressed the dark matter pouring in from Ren inside the fictional armament.
"Onii-chan, just a bit more."
"...Got it."
I focused my mind, not letting the fictional armament collapse.
The fictional armament showed a hint of red color. Perhaps this was the color of Ren's thoughts.
"—This is everything."
Then Ren's dark matter was all poured into my fictional armament.
I turned all that dark matter into a single bullet.
Transmuted into golden particles that caused souls to materialize—
"Ether Bullet!!"
The fictional armament vanished the moment the bullet was shot.
The golden bullet, with everything of Ren's and mine poured in, shot high into the sky. Giving off intense brightness, it then exploded.
Instantly, the sky's color turned from pale blue to a dazzling golden.
Glittering brightly, the radiant particles drifted down from the sky.
It was finer than snow—Like golden diamond dust.
Descending from the sky, the Ether Wind gradually covered Yggdrasil's collapsing main body.
"How is it...?"
I observed the situation with bated breath.
If Director Miyazawa's predictions were true, then Yggdrasil's mind ought to manifest.
Amidst the drifting brightness, an outline gradually surfaced.
A scene just as hoped, but—
"This is... impossible."
Ariella muttered blankly.
The others gasped in surprise.
I did not make a sound, simply shocked by the sight before my eyes—
Yggdrasil's soul was gradually materializing as though flooding out of its collapsed body.
It was an outline of a giant tree, whose branches extended to the other side of the horizon, completely blotting the sky.
Its size was not merely 5000 meters, but much more gigantic.
Seeing its outline cut off unnaturally, I could tell that what the Ether Wind caused to manifest was merely a small portion of the whole.
This gigantic soul, how do we destroy it?
Only then did I realize we were too naive.
Yggdrasil's true nature was a network built from all the plants in the world. On further thought, it would not be strange even if its soul was on the scale of the Earth.
Just as all members of Brynhildr Class were stunned. Kili quietly looked up at Yggdrasil and turned towards me.
"Yuu? Aren't you going to fight? You're destroying that thing, right?"
"—!"
Her words prompted me to regain my senses.
Indeed... By this point, there was no choice but to do it. This was surely Yggdrasil's core without a doubt.
No matter how despaired, for the sake of everyone who had brought me here, I must not give up!
"—Ren, I'm going to borrow dark matter from you again, to construct an anti-dragon armament this time."
"Mm!"
Ren's eyes blazed with fighting spirit. She gripped my right hand firmly.
"Anti-dragon armament Marduk—Psionic multi-barreled cannon, Noah!"
I transmuted the dark matter flowing from Ren into a pre-civilization weapon.
Performing transmutation using blueprints in the mind was much easier than making a fictional armament.
A double-barreled turret appeared on a rotating artillery platform. With a design of glowing lines carved on its surface, the multi-barreled cannon was linked to my consciousness, aimed at Yggdrasil.
As a weapon that amplified and shot out the gunner's thoughts, Noah was effective against spirit bodies which did not interact with ordinary matter. This was already proven during the battle against Hraesvelgr.
—I will defeat you. I won't become your possession!
"Fire!"
Turning strong willpower into energy, Noah's multi-barreled turret fired two shells.
The shells struck the materialized spirit body, causing golden particles to fly into the air.
However, Yggdrasil's spirit body was far too humongous. These tiny shells did not produce much trace of destruction.
"—Fire! Fire! Fire!"
Even so, I still fired relentlessly.
But the more I repeated, the more I realized that my attacks were equivalent to a toy gun against Yggdrasil's spirit body whose size was extraordinary.
Even if I were to shoot dozens, thousands of times, I did not think I would succeed in destroying it.
My consciousness gradually grew hazy because the more I shot, the more mental energy was consumed. Even if I increased the number of turrets like during the battle against Hraesvelgr, it was pointless because my mind's energy was limited as the source.
"Fire—Huff, huff, huff..."
After who knew how many shots had been fired, I breathed heavily. My vision was blurred from the sweat entering my eyes. I could see Yggdrasil's spirit body standing upright, completely unshaken.
"Damn... it..."
There was no time left.
The Ether Wind scattered earlier was fading bit by bit.
"Onii-chan..."
Ren looked up at me with worry.
"I'm fine... I can still shoot."
I feigned vitality and forced myself to answer, then glared at Yggdrasil's spirit body that had appeared due to the golden particles.
I must endure... As the only one capable of attacking spirit bodies, I could not rely on the others.
I had relied so much on them beforehand, so I must accomplish this—
But my knees gave way.
My body was about to fall over forwards.
I slowly approached the ground... But stopped just before my face smashed the ground.
"Huh...?"
I came to my senses only to find Mitsuki, Iris and Tia's face before me.
"Nii-san, are you okay!?"
"Mononobe!"
"Yuu!"
The three voices sustained my consciousness that was about to be cut off.
"—Thank you all."
I thanked them and got up, but this time, I fell backwards.
However, warm hands caught me this time too.
"Goodness gracious, get a grip on yourself and stand properly."
"Do your best, Mononobe-kun."
"Mononobe-kun, hang in there."
Lisa, Firill and Ariella supported my body from behind.
"Sorry. Thanks."
I thanked them. Standing in the distance all alone, Kili asked me:
"Yuu, are you at your limit?"
"No... Not yet. I feel power surging from within."
This was not pretense. I really did feel I could continue to fight fiercely.
My heart felt very warm and it seemed like the mental energy I had depleted had recovered a little.
However, this was surely just my own wishful thinking.
Thoughts or mental energy could not be transferred to others like dark matter.
—When this thought crossed my mind, a question occurred to me.
Really... Is that true?
Who decided that mental energy could not be transmitted? When was it proven?
Through training with Ren, I found out that dark matter from other people consisted of fragments of the mind—fragments of thoughts and feelings.
The transfer of dark matter was equivalent to sending your thoughts to someone. To sustain the psionic multi-barreled cannon, Ren's dark matter continued to flow.
Was dark matter really the only thing Ren was giving me?
Those hands, tightly held together, supporting my heart, perhaps that kind of power would—
"Everyone, can I ask you for a favor?"
I asked the girls.
"What is it? I am willing to do anything in my power for you, Nii-san!"
Mitsuki instantly answered and the others urged me to tell them.
"I hope you will transmit your thoughts to me using the same principles as dark matter transfer."
I did not know if this would actually pass mental energy over. Even if it could, it would probably serve as merely psychological consolation.
But in order to fight to the very end, I sought everyone's power.
"Thoughts...?"
Iris widened her eyes, cocking her head in puzzlement.
"Yes, lend me your thoughts... the power of your heart and soul."
"—I understand. Just thoughts and feelings, isn't that right?"
Lisa nodded, applying force through her hand that was supporting my back.
"Mononobe-kun... I will think of you as strongly as I can."
Gripping my shoulder firmly, Firill spoke.
"I will cheer for you, Mononobe-kun."
Ariella said while touching my back.
My heart began to warm up. Everyone's thoughts were making me happy. My mind gradually felt satisfied.
Was this mental energy flowing in? Or simply the effect of receiving encouragement? I did not know actually.
But my originally sapped strength surged again, this was the truth.
I slowly took the power received from everyone and poured it into Noah. The lines carved all over the multi-barreled cannon began to glow with dazzling light.
"Tia is always always thinking of Yuu!"
"Nii-san, please accept my thoughts!"
Tia and Mitsuki pressed their hands on my chest, praying strongly.
Then Iris placed her hands on top of theirs.
"Mononobe—"
Iris simply called my name and smiled faintly.
But I could feel it. I could feel Iris' thoughts. I could feel intense feelings that made my chest hot.
Not only Iris but Tia and Mitsuki's emotions and words were giving me power.
The multi-barreled cannon, which converted mental energy into shells, rumbled, giving off light that shone all around.
"Onii-chan...... Don't lose!"
Gripping my right hand tightly, Ren cried out as hard as she could.
Ren's thought flowed into me together with her dark matter.
I could feel the unprecedented power of thoughts, dense and fierce, gradually growing stronger inside the anti-dragon armament.
Everything was poured into this one attack.
Let me fire the thoughts and feelings of insignificant humans towards Yggdrasil.
Let it know that we are living with such fiery emotions in our hearts.
"We're doing it, everyone."
"Yes!"
The girls responded to my call.
Then in unison, we fired our thoughts.
"FIRE!"
An intense glow expanded from the two muzzles, shooting at the sky. While firing, the psionic multi-barreled cannon exploded from within and collapsed.
The two balls of light melded together, forming a gigantic shell, striking Yggdrasil's spirit body.
Immediately exploding with blinding light, golden particles then scattered all over the sky.
The atmosphere shook slightly. The outline of Yggdrasil composed of Ether Wind shook for an instant.
Once the particles scattered and disappeared in the air, I could see a massive hole opened up in the center of Yggdrasil's spirit body.
However, the spirit body showed no signs of overall collapse.
"Damn it! This didn't work either..."
I said with frustration.
"Onii-chan... One more time."
Ren pulled my hand. She did not show any signs of giving up in her expression.
"—Yeah, until it's destroyed, we'll shoot no matter how many times it takes."
I nodded and prepared to construct the anti-dragon armament again, but Kili stopped me.
"No, this is good enough."
Kili approached me and smiled with satisfaction.
"Enough...? Yggdrasil's core consciousness isn't destroyed though."
"But damage has been inflicted, so next is your job—Tia."
Kili patted Tia, who had been lending me power, on the shoulder and said to her.
"Tia's job?"
Tia widened her eyes and stared at Kili.
"You should be able to hear it, right? Yggdrasil's screaming."
"...Yeah, but it's a mess. Can't hear what it's saying."
"That is evidence that the core's functionality is damaged. Given now, Tia, you'll surely prevail over Yggdrasil."
Kili grinned and continued.
"Your pair of horns is not simply for defending against Yggdrasil's interference. It is a weapon existing for the sake of devouring Yggdrasil, a power to enable you to become a dragon."
"The horns are a weapon... Become a dragon—"
Tia touched the horns on her head, apparently thinking of something.
"Against Yggdrasil that's trying to take Yuu's place, just do the same thing to it. Tia, you have that power."
"—Yeah!"
Tia nodded. Looking like she understood what she must do, she constructed her wing-shaped fictional armament on her back.
"Hey Tia!"
Before I could stop her, Tia had already flown into the sky, heading for Yggdrasil.
"Kili, what are you planning to have Tia do!?"
I glared at Kili and asked her what was going on.
"I simply presented a choice. Everything is Tia's own decision. Don't belittle her resolve."
Glared back by her with such intense emotions, I could not help but gasp.
"Mind your own business and quietly watch Tia's battle."
Kili spoke in a sharp tone of voice to stop Lisa and the others from chasing after Tia.
"You will soon know what Tia is about to do."
Staring at Tia in flight, Kili spoke quietly.
Tia arrived at Yggdrasil's spirit body then jumped into the hole I had punctured.
Several seconds later, blindingly bright lightning erupted with Yggdrasil as the center.
Flying through the air where golden particles drifted, Tia Lightning recalled the first time she met him—the time when she encountered Mononobe Yuu.
Back then, Tia did not quite understand much about herself.
Her parents called her human but demanded her to create gemstones through transmutation.
Later on, Tia and her parents were captured by an armed gang. This time, she was exploited as a D with the power to generate dark matter.
Hence, Tia had asked him—Mononobe Yuu who had rescued her from that armed gang—What am I?
Then with broken speech, he replied in Tia's mother tongue:
'You are a—cute, girl.'
It was a very gentle answer.
Tia wanted to become like that, hoped for herself to become like that, it was the answer Tia desired too.
Tia had always kept those words in her heart.
Meeting Kili, raised to become a dragon, selected by Basilisk—Tia had abandoned that dream once... But after reuniting with him and rescued by Lisa and the others, Tia made a decision as a result.
Tia would live together with Lisa and the others as humans.
To become the cutest girl of all in Mononobe Yuu's eyes—to become his wife.
Then like how he had protected her, she would protect him too.
"Tia will save Yuu!"
Tia generated wind from her fictional armament, a pair of red dragon wings, and charged into the interior of Yggdrasil's spirit body.
Her surroundings were covered by golden particles, so bright that her eyes could almost see nothing. Tia heard Yggdrasil's cries in her mind.
'Thought, flaw—collapse, reject—reject, reject, reject, repair, prioritize—'
Not just a voice. Through her horns, Tia could sense intangible feelings.
"—It's afraid."
Tia murmured.
Yggdrasil was afraid. Afraid of its consciousness disappearing, afraid of losing its existence, afraid of eath—Extremely extremely frightened.
'Neun—needed, must have—uncertain, ninth authority, one and only—most suitable, survival strategy—'
And it wanted—
To survive, it needed Mononobe Yuu.
Tia could sense this concretely.
Tia did not know what it was afraid of. Yggdrasil's thoughts were fragmented, incomprehensible.
However—
"You're not having him!"
Tia declared to Yggdrasil in no uncertain terms.
"Because Yuu will become Tia's husband!!"
Tia poured all her thoughts into dark matter, transmuting it into electricity then released it.
Tia's consciousness spread as an electromagnetic field, expanding inside of Yggdrasil.
Attacked and damaged by Noah, Yggdrasil's core system had encountered a bug, allowing Tia's consciousness to invade.
Hacking into Yggdrasil, this was precisely the true function of the pair of horns given to Tia.
"...!"
Intense pain struck her head, causing Tia to frown. Yggdrasil was resisting, it was struggling, trying to evict Tia's consciousness that was invading in the form of electrical signals.
"Tia won't lose... This time, Tia will protect Yuu!!"
Using willpower as fangs, turning emotions into claws, Tia bit and ripped apart Yggdrasil's consciousness.
Tia's thoughts were endlessly amplified by the electrical energy obtained through the transmutation of dark matter, gradually conquering the core system.
The golden particles shrouding the surroundings shook. It was a sign that Yggdrasil's spirit body was starting to change.
'—Reject, reject, reject, unacceptable, overload, unacceptable—destroy, reject, reject—!'
Yggdrasil resisted desperately but the CPU had been destroyed physically, the mind was damaged, and right now, its computational power had dropped to its limit.
Conversely, after devouring Yggdrasil's consciousness, Tia's thoughts had acquired overwhelming processing power.
But due to excessive expansion of her ego, her original self turned fuzzy. Having obtained processing power that was originally impossible for humans to have, Tia's mind could not keep up with her thoughts.
"Tia is... what?"
Amidst her expanding ego, her consciousness was wavering.
But his words, carved deeply in her heart, kept Tia's consciousness together.
—You are a—cute, girl.
Tia gritted her teeth and used her dark matter to the limit to use her thoughts to rewrite everything.
"That's right... Tia... Tia will become Yuu's wife!!"
Then her will raced along the network formed from plants, exploring Yggdrasil's true nature.
Then she understood. The power to control electricity was merely one part of Yggdrasil's true nature.
The name of the authority was: Akashic Record.
There, Tia caught a glimpse of everything.
Composed of golden particles, Yggdrasil's mind twisted and changed in shape.
The gigantic body, never collapsing no matter how many times Noah attacked, changed in form as though melting.
"Tia... What did she do?"
I looked in surprise but I was soon struck by even greater shock.
Shaking, gradually fading away, the Ether Wind proceeded to trace out a certain outline.
Instead of a giant tree, it was the silhouette of a young girl.
"Tia-chan...?"
Iris cried out in surprise.
Indeed—The golden particles were undoubtedly showing the figure of Tia Lightning.
"Looks like it's a success. Tia has already taken control of Yggdrasil's core."
Kili smiled happily and explained to us.
"What... Control of the core?"
Since it was too shocking, I could only repeat like a parrot.
"Yes, capable of outputting thoughts as electrical signals, right now, Tia can electrically interfere with senses, in other words, hack into Yggdrasil then tamper with the core, forcing the system to recognize her as the new core."
Kili replied so nonchalantly, but after seeing the Ether Wind fade away, she smiled.
"From the start, I raised Tia intending to have her devour Yggdrasil. But back then, I had no idea that Yggdrasil was such a terrifying monster. If we had challenged it normally, I think we would've failed already. It's all thanks to you inflicting damage to the core, Yuu, that we succeeded on this occasion."
The golden particles scattered amidst the sky's morning glow.
The particles showing Tia's image also disappeared gradually.
Visible under the particles was Yggdrasil's collapsed remains and a girl with a pair of radiant wings on her back.
Looking up at the young girl flying back to our side, Kili said proudly:
"Look, Yuu, this is the new dragon I raised—Tia Lightning Yggdrasil."
