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.

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...

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...