A man who was playing a game in Japan, dies of cardiac arrest. In the brink of death, he was requested a mission: 「Please, save the world from the tyranny of the hero that defeated the Demon Lord, who was seduced by the heroines to do evil.」, a favor by the Goddess of the eroge he was playing.
With the knowledge of Modern Age of our world and Summoning Magic, this is a story of a man who conquers the heroines of the hero, before the hero does.
Reincarnates as the villain of the game, tries his best in economics, technology, capturing the heroines, and saving the world.
※ No worries, this does not have 18 rating, and there is no NTR or Netori.