Toshimitsu Saigō, a classmate of the protagonist at Oedo Elementary School, solidifies his status as "the boss" of their peer group through assertive dominance. He regularly engages in teasing and antagonizing the protagonist, fueling comedic clashes within their interactions. His dynamic extends to Ganmo, whom he notably shoves during a confrontation, underscoring his role in amplifying chaotic scenarios.

Consistently present across multiple episodes of the main series, he remains a fixture within the school’s social hierarchy. The 1985 film adaptation similarly features him in a secondary capacity, retaining his established persona. Defined by a brash, confrontational demeanor, he perpetuates friction in the protagonist’s daily experiences. No familial ties, personal history, or character evolution are explored in available sources.

His documented involvement remains limited to the core series and film, without expansion into spin-offs, OVAs, or supplementary media. The narrative maintains his initial portrayal, omitting arcs that diverge from his role as a perpetual instigator.