Although the Demon Possession that caused the large-scale power outage was exterminated, the problem remains unresolved as the power shortage in Bayron City continues. Meanwhile, Kisara witnesses a secret meeting between Ayano and a mysterious man. To confirm Shu's feelings, she uploads a photo of the scene to social media. Successfully lured by Kisara, Shu rushes Ayano and the mysterious man – an Anti-Demon Bureau detective named Tetsuya Mikami – and, in an unexpected flow of events, realizes that Ayano was hiding her intentions and planning behind his back. An unparalleled sense of tension lofted between the two.

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?