Movie
Description
Tatsuo Nagumo is a seemingly ordinary, shy, and lecherous high school student whose life shatters when supernatural forces identify him as the destined vessel for the Chōjin (Overfiend). This god-like entity is prophesied to unite the human, demon, and man-beast realms every 3,000 years, making Nagumo a target for demons and man-beasts seeking to control or eliminate his latent power.

He develops a romantic relationship with classmate Akemi Itō. While anime adaptations portray Akemi as innocent and compassionate, the manga depicts her as more sexually adventurous. Their bond becomes central to the prophecy, as Akemi is fated to bear the Chōjin's offspring. Nagumo's connection to the Chōjin manifests through involuntary, Jekyll-and-Hyde transformations. During extreme arousal or danger, he mutates into the violent "Demon of Destruction," committing killings he cannot remember afterward.

Driven by jealousy over Akemi and manipulated by the demon Suikakujū, classmate Yūichi Niki undergoes a grotesque transformation, replacing his genitalia with a demonic phallus for power. This leads to a fatal confrontation where Nagumo, in his demonic state, tears out Niki's organs. The prophecy is ultimately revealed as a misinterpretation: Nagumo's transformation into the Demon of Destruction triggers an apocalyptic cataclysm, devastating the human world to facilitate the birth of the true Chōjin – his child with Akemi.

In later arcs, Nagumo fully becomes the Demon of Destruction. His actions escalate to global devastation, annihilating cities and populations to forge a path for the new world order under the Chōjin's reign. Akemi, protected by the Chōjin's power, remains unharmed, even from her own suicide attempts.

Adaptational differences exist: the manga confines the conflict to human and demon realms, while the anime introduces the man-beast realm, expands Nagumo's interactions with beings like Amano Jyaku, and amplifies the apocalyptic scale, depicting the merging and ruin of all three realms. Post-apocalyptic stories focus on the survivors and the rise of the Chōjin, with Nagumo's direct involvement diminishing after fulfilling his destructive purpose.