The story follows an international training organization named Babel which protects the young people returning from another world. A wayward hero named Akatsuki has come back to the real world from a world of sword and magic called Areizaado, alongside a beautiful girl who is a demon king's daughter.

In normal RPGs, a hero defeats the Satan king and the story ends. But what does the hero do after that? Ohtorizawa Akatsuki defeats the Satan king in the fantasy world of Alleyzard and returns to the real world. He is sheltered by the international organization BABEL, which protects and controls people transferred from the outer worlds. BABEL is astonished to know Akatsuki has really defeated Satan and brings Satan's daughter Miu from Alleyzard. In the academy of BABEL, Akatsuki confronts other "returners", who have psychic powers.