Onii-san holds the role of otokoshi within the maiko house, a professional male position dedicated to assisting maiko and geiko, specifically with the complex process of dressing in their kimonos. His duties encompass general household support, including physical tasks like moving heavy objects; he helps Kiyo by shifting a refrigerator so she can retrieve a book that fell behind it. He operates as part of the maiko house's daily functions under the head of the household, Okaa-san. Information regarding his full name, place of origin, personal background, or development across seasons, films, or other official media adaptations does not exist.