Hyodo Issei is a second-year student at Kuo Academy, normal and ordinary but perverted and lascivious. He leads a quiet life until a girl, Amano Yuma, offers him a date. Of course, this is not something normal: the girl is a fallen angel who wanted to kill him.
With no possible salvation, Issei dies, but is immediately reincarnated as a demon under the command of Rias Gremory, a high-level demon girl who happens to be the most beautiful and popular girl in school. Thus, Issei is trapped in a war between angels and demons that comes from ancient times. But all is not as terrible as it seems…