At Kuoh Academy, a former all-girls school that has recently turned co-ed, the students consists of humans, angels, fallen angels and devils. One of these students, Issei Hyodo, is a lecherous second-year human student there who lives a peaceful life. After an ordinary school day, Issei is asked to go out on a date by a girl named Yuma Amano. Later, Yuma brings Issei to a local park and tells him that she wishes for him to die for her. She reveals herself as Raynare, a fallen angel. Issei is nearly killed by Yuma. Using his summoning card, Rias Gremory, a buxom third-year student at Kuoh Academy, revives him. Issei wakes up the next morning, thinking that the events that occurred were all just a dream. Immediately after being attacked by another fallen angel and waking up, he notices Rias naked in his room. Rias reveals her true identity as a devil to Issei and says that she has reincarnated him as a devil, becoming his new master in the process.