Based on the erotic game by Guilty Nightmare Project.

Rinne Natsume is a very ordinary schoolgirl, she lived her life thinking that... until she found out her secret. A few months ago, she was attacked by a devil cult and lost her father. At that time, she awakens the power of the "god of death" that she had been harboring inside her, and defeats the cultists. Her momentary peace does not last long, and she is taken prisoner. Akuto, the head of the cult's branch, turns the brunt of his resentment toward Rinne for the wounds inflicted on him by Rinne's father. Now, the sacred mating ritual between the devil and the god of death is about to begin. Then, wandering exorcists Setsuna Shindou and Yuuka appear! However, despite their best efforts, they are surrounded by a large number of believers... What is waiting for them at the end of this desperate situation!?