Kurumi Satō is a third-year student at Usakame High School and a member of the school's tennis club. Her family runs a roasted bean shop in the local shopping district, a background that has given her a particular skill for preparing bean dishes and picking up individual beans with ease. In terms of personality, she is calm and has a natural airheaded quality, a gentle and slightly ditzy demeanor that makes her likable and approachable. She is highly sociable, never shying away from conversation even with strangers, and this openness contributes to her being well-liked by those around her. One distinctive visual trait is the adhesive bandage-like mark on her left cheek.

Within the story, Kurumi is part of the core quartet of the tennis club, whose daily activities and humorous interactions drive the comedy. She acts as a relaxed and somewhat dreamy presence among the more eccentric club members. As a third-year student, she is facing her final tournament with the club, which adds a layer of personal significance to her participation. Her development is noted by a visible growth since starting her final year, though the narrative portrays this with the same light, offbeat touch that defines the show's tone. In addition to her bean-related talents, she has a comedic ambition to master a supposedly unguardable tennis technique called "Death Requiem," which reflects the series' playful approach to sports and club life.