Kojirō Kirishima is a supporting character in The Yuzuki Family’s Four Sons. He is the grandfather of Uta and Waka Kirishima, the neighboring family of the Yuzuki household. Despite being an elder, Kojirō forms a close and meaningful friendship with the youngest Yuzuki brother, Gakuto. Their bond begins when Kojirō treats Gakuto with the same respect he would an adult, introducing himself by name and asking for the boy’s preferences rather than speaking down to him. This gesture moves Gakuto and sparks a connection that develops into a genuine, cross-generational friendship. Kojirō shares Gakuto’s interest in period dramas and shogi, and the two spend time together watching television and playing board games.

Kojirō’s personality is defined by a calm, approachable manner and a sincere respect for others regardless of age. He does not condescend to children but instead engages them as equals, which makes him a trusted confidant. His motivations appear to center on genuine companionship; he enjoys simple, shared activities and values the time he spends with Gakuto and his own grandchildren. Within the story, Kojirō serves as a link between the Kirishima family and the Yuzuki brothers, reinforcing the series’ theme that family extends beyond blood ties to include the wider community. He provides Gakuto with a friendship that is distinct from the boy’s relationships with his older brothers—one based on mutual interest rather than caregiving.

While Kojirō does not undergo a dramatic personal arc, his role illustrates the importance of intergenerational kindness and the ease with which meaningful bonds can form when people treat one another with basic dignity. His notable ability lies in his natural talent for connecting with others, young and old alike, simply by being present, courteous, and genuinely interested in their lives. Through his interactions with Gakuto and his own family, Kojirō embodies the quiet, steady support that helps the series’ world feel interconnected and warm.