Kohoki, a demon exiled to Hell a century earlier for his illicit romance with human Megumi Amano, is resurrected by Münchhausen II—a descendant of a Nazi scientist determined to awaken the primordial entity Kyō-Ō. Bound by alliance, Kohoki shares critical knowledge of the three interconnected realms (human, demon, and man-beast) and the prophecy of the Chōjin, a supreme deity fated to unite them. He assists in orchestrating a passenger plane sabotage targeting Takeaki Kiryū, a relative of the Chōjin’s host, triggering Takeaki’s metamorphosis into Kyō-Ō’s corrupted vessel. When commanded to kill Megumi, Kohoki’s lingering affection overrides his obedience. Defying Münchhausen II sparks a violent clash, ending with Kohoki’s mind ensnared by occult control. Later, confronting Megumi’s brother Amano Jyaku in battle, Kohoki suffers defeat but seizes a final chance at redemption. With fatal wounds weakening him, he intercepts a lethal strike meant for Megumi, breaking free from Münchhausen II’s influence through his sacrificial death. Exclusive to anime adaptations and OVAs, Kohoki’s narrative extends into later arcs, featuring alliances with rival antagonists and engagements in apocalyptic struggles, though precise developments remain sparsely detailed.