Umibozu, formally named Hayato Ijuin, is a seasoned sweeper and ex–Special Forces operative whose adversarial beginnings with Ryo Saeba forged an enduring rivalry. The moniker “Umibozu” (sea monk), earned during their clash in a Central American civil war, reflects their origins on opposing fronts—Umibozu as a government soldier, Ryo as a guerrilla insurgent. Though once enemies, their confrontations morphed into a grudging alliance, punctuated by tactical teamwork on Tokyo’s perilous cases.

A master of heavy weaponry and demolitions, Umibozu serves as a secondary protagonist, countering Ryo’s showmanship with stoic discipline and methodical combat strategies. Between missions, he grounds himself at Cat’s Eye café, working under Miki, a former wartime comrade and past romantic partner. This veneer of civilian normalcy belies his entrenched ties to Tokyo’s underworld, where his tactical acumen remains in high demand.

Central to his arc is an unresolved challenge: a long-deferred duel with Ryo to settle their rivalry definitively. Though Ryo evades confrontation, Umibozu’s determination persists, undimmed even by the incident that cost him his sight—a consequence he accepts without bitterness. His Smith & Wesson M29.44 Magnum mirrors Ryo’s Colt Python, their firearms emblematic of their clash in styles: calculated force versus precision agility. Yet these contrasts fuel their effectiveness as uneasy allies in high-risk operations.

Childhood conscription and wartime trauma shaped Umibozu’s reserved demeanor, though flashes of dry humor surface among trusted allies. His rigid ethics, prioritizing civilian protection above all, align unexpectedly with Ryo’s own code, bridging their divergent methods. Across iterations, he remains a stabilizing force—a taciturn counterpart to Ryo’s theatrics, anchored by unspoken respect and the quiet thrum of rivalry.