Isamu Ōyama serves in a futuristic private security force, his muscular build and rugged demeanor underscoring a career built on physical prowess. A brash first encounter with a tomboyish colleague—mistaking her for a man and provoking a swift, forceful retaliation—exemplifies his confrontational humor and tendency to disregard social subtleties.

A veteran of unspecified military service, he prioritizes tactical efficiency and bodily discipline within the team, though his blunt demeanor occasionally strains alliances. Romantically fixated on a female teammate, he pursues her with unapologetic candor, their escalating trysts blurring professional boundaries during missions.

While camaraderie binds him to the unit, tensions simmer over clashing priorities: his focus on combat readiness contrasts with others’ emphasis on interpersonal cohesion. The narrative frames him strictly through his present role, omitting deeper origins or evolution beyond his dual identity as both disciplined operative and recklessly passionate figure entangled in workplace indiscretions.