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 middle of the battle against the demons on the artificial island, Kisara was stabbed by a spear before Shu's eyes. Saved by Ayano and Sharon, Shu helplessly evacuates from the fight when he sees the person he's been looking for—his younger sister, Kanna. Then, humanity's desperate resistance, backed by the focused efforts of Bayron City, proves futile as the extent of the large-scale disasters caused by Kanna, now certified as an S-Class demon, expand. Kisara collapsed due to her injuries and lost consciousness as her vitals disappeared. Unable to move, Shu just stares at her. And as if responding to his heart, Kisara gently awakens.

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?