Norio Tsukumoin is a 34-year-old male with black curly hair, brown eyes, and two beauty marks beneath his left eye. He presents as tall and handsome, typically dressed in a black suit. As head of Tsukumoin Bank, he was raised as the family heir, mirroring the upbringing of his close friend Tadashi Miyanomori.

His personality blends seriousness and confidence in professional settings with a relaxed, protective nature in personal relationships. He displays occasional arrogance alongside deep emotional vulnerability. Norio shares a long-standing friendship with Tadashi dating to their school days, built on mutual trust and lighthearted teasing. This includes a bet about who would marry first, later retracted by Norio.

Norio develops a significant romantic relationship with Kurenai, a geisha at Yasuda, owned by Shizuko Yasuda. His feelings lead him to challenge social conventions, declaring a willingness to "break rules" to be with her. This commitment sparks tension with Tadashi, who initially opposes the relationship. External pressures cause Norio to temporarily abandon his pursuit of Kurenai, creating a rift between the friends. They later reconcile when Norio acknowledges Tadashi's behind-the-scenes efforts to support the relationship through Yasuda connections. Norio ultimately seeks Tadashi's active help to secure a future with Kurenai, demonstrating persistent affection.

His dedication extends beyond romance; his stated hobby is simply "to be with the ones he loves." This drives his efforts to maintain the friendship with Tadashi despite conflicts. During their reconciliation over Kurenai, Norio displays emotional vulnerability, crying while expressing his feelings. He also interacts socially with the Miyanomori family, attending events like a beach gathering hosted by Tadashi and participating in functions alongside the brothers.