Issei Hyodo is a struggling hormonal teenage boy. He thinks things are beginning to turn around for him when he scores a date with a seemingly shy girl named Yuma. After his date he soon realizes the girls at his school are far more complicated than he could have ever imagined.

While still coming to terms with his new life as a devil, Issei learns the truth about Yuma.

Issei makes a new friend when he meets a nun named Asia Argento, but his identity as a devil and her position in the church make for a complicated union.

Issei finds his attempts to spend time with Asia to be continuously thwarted. When he must save his new friend, he realizes that he is far more powerful than he had given himself credit for.

Issei learns his ex-girlfriend Raynare will go to extreme lengths in pursuit of power and her efforts may kill Asia. If he's going to save her, he'll need to draw forth the strength he never knew he had. But will it be enough?

Issei needs to improve his physical fitness, so Rias helps him begin a grueling training routine. Meanwhile, Asia settles into a new living situation and a new school.