Sachio, a former street child aligned with the Team Nowhere gym, was once among a group of orphans sheltered by Coach Nanbu. By the second season’s events, he emerges as a young adult consumed by resentment toward Joe, the protagonist, blaming him for Nanbu’s death. This fury originates from Joe’s choice to compete in a high-stakes boxing match to fund Nanbu’s medical care—a gamble that failed, leaving Nanbu to perish alone while Joe was absent.

His bitterness erupts in violent clashes, like a brawl that shatters a local eatery after confronting those threatening his friends. This forces Joe into a rigged bout to reclaim the restaurant’s deed, worsening their fractured bond due to Sachio’s hatred for orchestrated fights. Though fiercely protective of his community, Sachio remains inexperienced in the ring, often defeated and dependent on others to mend the chaos he sparks.

Flashbacks unveil Sachio’s pivotal role in driving Joe into self-imposed exile, openly accusing him of causing Nanbu’s demise and casting him out. This rejection fuels Joe’s downward spiral and prolonged disappearance. Their tense encounters underscore unresolved guilt and the thorny road to forgiveness, as Sachio grapples with fury toward Joe yet clings to vestiges of their fractured kinship.

His arc illustrates trauma’s enduring impact and the fragile process of restoring trust, positioning his choices as a lens for examining responsibility, redemption, and the weight of unresolved grief within the narrative.