Amano Jyaku, a demon-human hybrid from the man-beast realm, is tasked with locating the Chōjin—a prophesied entity capable of uniting or annihilating worlds. Born to a human and a demon, his banishment to Earth by the Great Elder stems from misconduct involving Mimi, the Elder’s granddaughter. His portrayal splits across media: the manga frames him as a manipulative hedonist, exploiting deceit to seduce others under the guise of granting protective powers through his sperm, driven solely by self-interest. Anime adaptations reimagine him as a laid-back yet noble guardian committed to protecting the Chōjin and balancing realms, guided by the Great Elder to understand the entity’s true purpose.

In post-apocalyptic settings like *Inferno Road*, he navigates a monster-ravaged Earth, enduring its horrors while advancing toward a climactic clash between the Overfiend and the Lord of Chaos. His immortality sustains him, but he becomes an observer of humanity’s collapse rather than its redeemer.

Sequels showcase erratic character growth: early anime iterations present him as affable and morally steadfast, later derailing into selfishness in *Return of the Overfiend* before reverting to his principled roots. Dynamic alliances with figures like Suikakujū, a demonic rival turned reluctant ally, and Buju, a marauder pursuing redemption, reflect his shifting role in the series’ chaos.

Physical traits adapt across mediums—manga art gives him black hair and casual wear, while anime designs feature blue hair, facial scars, and a striking wardrobe, visually distinguishing his Adaptational Heroism from the manga’s morally gray antihero.

Central arcs involve thwarting realm mergers, safeguarding the Chōjin’s human host Tatsuo Nagumo, and clashing with power-hungry entities like Münchhausen II. His journey loops through cyclical timelines, reliving the saga’s origins as cosmic strife remains unresolved.