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...

Thanks to Shu and Kisara's efforts, the Anti-Demon Bureau successfully detained Sharon, and peace returned anew to Bayron City. With his companions Mikami and Miles, Shu once again pursues the truth behind the continuous D Hazards that have been manipulated by some entity's volition. They continue compiling deductions to pin down the identity of the "True Agent," who they presume is lurking behind Junya Hanamura, the murdered Demon Agent. At the pinnacle of their deductions, Mikami reaches a certain conclusion and tries to contact Shu in a hurry...

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?