Apocalypse Bringer Mynoghra, Vol. 1 (manga)

“I reincarnated as an evil god.” Takuto Ira, after dying from illness at a young age, is reborn into a world just like the strategy simulation game he loved in his past life, “Eternal Nations.” There, what appears before his eyes is a girl, Atou, whom he had used before in the evil civilization he previously subdued in the game, Mynoghra. The two resolve to create a new nation in this world once more.