Kisara is in a great mood after getting a duplicate key to Shu's apartment. On the other hand, Shu can't find any peace of mind when she gets ahold of the company's financial situation without permission and increasingly encroaches on his daily life by pretending to be his hidden mistress. But even more problematic is the current lack of living expenses. Shu finds out that the incoming deposit he was relying on is still on its way due to a misunderstanding, so he asks Ayano for some contract work. And thus, Shu and Kisara find themselves safeguarding the 25th anniversary party of Bayron City and protecting the mayor from terrorist threats.

Ayano has become a target for Demon Possession. Although Ayano narrowly escapes her first attack with Kisara's help, she begins a life of isolation to hide her Demonically Possessed eyes. Meanwhile, Shu is offered a chance to work together by Mikami, who is familiar with Shu's past. On board with the discussion, Shu discloses information to Mikami and his team at the Anti-Demon Bureau. They are trying to determine the identity of a Demon Agent producing Demon Possessions one after another. They step into a certain dwelling, but...

The memories Kisara stole from the demon revealed the truth behind the attack on Shu and his family 12 years ago. Asmodeus, a demon who changes their appearance, transcends time, has traveled around the world for over a century, created Demonically Possessed and inflicted harm upon humans. Like a hazardous calamity, Asmodeus is the bitter enemy that the Celestial Abbey hunts down. And the true enemy that killed Shu's father and took his sister. Moreover, this demon is supposedly involved in the origin of Orgonium, the root of Bayron City's success. It's now a battle for the city, no, for the fate of humanity and demons alike...

In the chaotic mix of humans and demons, Shu and Kanna meet in a violent clash worthy of their 12-year-gap as various motives intermingle in a battle engulfed by a sea of flames. Ayano, Sharon and Kisara try to somehow intervene in the siblings' fight that puts the fate of the world at stake. The only way to stop a powerful demon is with the power of a demon. Shu and Kisara join hands once again. Will the accumulation of their feelings reach Kanna, embroiled in her rage? At the end of the battle, what future lies ahead for humans and demons alike?