Yumi is the Yokozuna Jinou's wife.
She is strong-willed, sharp-tongued and blunt to a fault, but that's due to her no-nonsense attitude and little patience for shenanigans. As Jinou's wife, she tries her best to keep him under control, scolding him for crying in public and limiting how much he's allowed to drink in tournaments.
However, she shows a softer side when seeing how both Reina and Hinomaru care for each other, with the former seeking advice from her and her husband, and the latter defending Reina when Yumi told him to give up on her. She allows Reina to stay by hers and Jinou's side while she's in distress over Hinomaru's self-destructive behavior and also mentors her over what it means to be a rikishi's companion.