Sangoro lives as a child in Meiji-era Japan, residing within an economically stratified neighborhood bordering the Yoshiwara district. His family struggles with deep poverty; his father works as a rickshaw driver, placing them among the community's lowest socioeconomic strata. This hardship directly shapes Sangoro's life, leading to social marginalization and physical attacks from wealthier peers. After one beating, Sangoro actively hides the incident from his father, fearing disclosure would force his father to apologize to the attackers—a response revealing the power dynamics and familial pressures tied to their status.

Despite these challenges, Sangoro displays resilience and adaptability. He navigates his harsh environment without falling into lasting despair, contrasting with peers facing more overtly bleak futures. His path shows a pragmatic acceptance of socioeconomic limits; he finds a measure of contentment securing stable, adequately-paid employment as he approaches adulthood. This outcome highlights a form of limited agency within his constraints, where modest economic stability signifies a viable future compared to characters destined for exploitative work. Sangoro participates in street conflicts, including a notable fight at a local paper shop, illustrating the neighborhood's entrenched divisions and the children's navigation of them.

His relationships exist primarily within group interactions rather than deep individual bonds. Alongside peers like Midori (destined for the oiran life), Shota (from a moneylending family), and Nobu (connected to the priesthood), Sangoro embodies how familial roles and economic realities predetermine the children's paths. The narrative positions him as a secondary figure whose experiences reinforce themes of societal inevitability and resilience amid hardship, without extensive personal backstory or evolution beyond his established socioeconomic trajectory.