Boma, a shadowy mercenary with a criminal past, was forcibly transformed into a beast-human hybrid through judicial surgery—a punitive measure branding severe offenders with animal traits. His wolf-like grafts, masked by a cloaking hologram, allow him to pass as human while marking him as an escape risk under the law. Driven by the unresolved disappearance of his sister Usagi ("Bunny"), he navigates a fractured moral landscape, balancing ruthless efficiency with an unyielding loyalty to her memory.

Once contracted by crime lord Clair Leonelli to eliminate the android J, Boma defies orders, pivoting from adversary to reluctant ally. A master swordsman, he wields an imposing, unnamed blade with lethal precision, his combat skill matched only by a stoic, emotionally detached demeanor—a lingering scar from traumatic incarceration and bodily alteration.

Though positioned as a secondary figure, his dynamic with protagonists Daisuke Aurora and J exposes nuanced ethics: a mercenary bound by honor, capable of calculated violence yet driven by redemptive purpose. His arc culminates in a fragile truce with the central characters, torn between the cold pragmatism of his trade and a clawing pursuit of atonement, forever haunted by the ghost of familial duty.