Ibukimaru, an ancient oni and son of the legendary Shuten Douji, once abandoned his demonic heritage to forge a life in a tranquil village with a human wife. When authorities uncovered his true nature, they executed his spouse and desecrated her remains, spurring him to raze the nation in an inferno of retribution. This act condemned him to eternal imprisonment in Jigoku until his eventual return centuries later, driven by unresolved grief to seek his wife’s remains for proper burial.

As one of Jigoku’s Four Treasonous Generals, Ibukimaru wields superhuman strength, speed, and endurance, alongside energy projection through blade strikes and rapid regeneration. His pyrokinesis and explosive force mastery enable devastating attacks, complemented by shape-shifting his arms into massive kijin limbs for crushing blows. Further abilities include soul manipulation, flight, immunity to blood-based assaults, and resistance to electrical attacks.

A turning point arises when Ibukimaru forms an alliance with Rei Isurugi, a human consumed by yokai hatred. After Rei assimilates the oni’s soul, gaining his swordsmanship prowess, their dynamic shifts into an unexpected mentorship. Ibukimaru guides Rei to temper his all-consuming vengeance, channeling it into measured justice. Their combined strength proves vital in defeating the kitsune Tamamo-no-Mae during a decisive confrontation, marking Rei’s transformation from destroyer to disciplined warrior.

Though vengeance initially fuels Ibukimaru, his later choices reveal a complex duality: he retains his apocalyptic capabilities while strategically aiding conflicts against greater evils. His arc embodies narrative themes of redemption and moral ambiguity, framing him as a volatile yet layered force within the story’s unfolding battles.