Panic and violence erupt in the streets when Ryou Asuka reveals that there are demons disguising themselves as humans in addition to the ones that are openly terrorizing humans. Anyone who fails to hunt demons runs the risk of being violently killed. When Akira Fudou witnesses the aftermath of this happening to those he cares for, the delicate balance between his psyche and that of Amon—a demon he has fused with in an effort to fight back—is broken, allowing the powerful Amon to roam Earth once more. As Amon slaughters everything in its path, it remains unclear whether Akira will ever regain control. [Written by MAL Rewrite]

No anime background information.