The Celestial Abbey — — Publicly seen as advocates for philanthropy, they are the world's largest Exorcist group. The identity of the mysterious nun who suddenly appeared in Bayron City is one of the most dangerous persons in the Celestial Abbey, Sharon Holygrail. Known as "Sharon the Chaste," she is one of the 12 remarkable Exorcists called "Living Relic." The Anti-Demon Bureau faces a growing sense of danger with the emergence of a new power that could shake the framework of their organization. Meanwhile, as Shu is injured and sleeping, Kisara tells Ayano about the events atop the snowy mountain that led to the intertwined fate of her, Shu and Sharon.

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?