Kaito emerges as a central antagonist from a fractured circle of childhood friends—Shuichi, Elena, Honoka, Naoto, and Aiko. Once cheerful and enthusiastic, his psyche fractured after a devastating misunderstanding: Convinced Aiko killed Honoka, he murdered her, only to uncover Honoka had stolen Aiko’s identity following the latter’s suicide. Consumed by guilt over killing Honoka, he spiraled into nihilistic detachment, pursuing immortality by bargaining with an alien entity. The pact required collecting 100 coins to secure his wish. Upon achieving immortality, his body transformed into an indestructible vessel regenerating through centipedes infesting his form. Dubbed "Rebirth," this power also let him reanimate and dominate corpses before decomposition, erasing their autonomy. Driven by a warped belief in Saṃsāra—existence’s cyclical nature—he dismissed death as illusory, enforcing his justice by exterminating those he judged sinful. His backstory traces a path into moral decay. After Honoka’s death, he petitioned the alien being to "make everyone disappear"—a wish with ambiguous parameters. This granted him dominion as an omnipotent collector, guarding the entity’s spacecraft and imposing his ideology through brutality. Confrontations with former allies like Naoto exposed his unyielding dogma: Opposition warranted annihilation, reflecting his twisted moral absolutism. Physically, his appearance shifted to mirror psychological fractures. During emotional peaks, his features contorted grotesquely—eyes hollowed into shadowed craters, a skeletal nasal cavity, and a pale mist exuding from his frame, manifesting tainted power. These mutations underscored his severed humanity and monstrous evolution. His arc climaxes in a cataclysmic duel against Shuichi, who vanquished him in an amalgamated abomination form. Though his reign ended, echoes of unresolved consequences lingered—trauma festering among the remnants of his former allies, their bonds irrevocably shattered.