Kureha Sakamachi is a first-year high school student and the younger sister of protagonist Kinjirou Sakamachi. Her mother was a champion wrestler, and Kureha has inherited a passionate love for the sport. This wrestling enthusiasm often spills into her daily life: she wakes her brother with painful submission holds and freely tests new moves on him whether she is upset, excited, or simply playful, turning their sibling interactions into a recurring physical comedy.

She is a member of the school's crafts club, yet her energetic and tomboyish nature dominates her personality. Kureha is optimistic and straightforward, rarely hiding her feelings. Her involvement in the central plot begins when she follows Kinjirou and the butler Subaru Konoe. Tragically misreading the situation, she becomes convinced that Subaru is a male pervert who has somehow ensnared her brother. Acting on this belief, she attacks Subaru to reclaim Kinjirou, only to be easily defeated in the confrontation.

After that fight, Kureha’s attitude toward Subaru shifts dramatically. Still operating under the false assumption that Subaru is male, she develops a heartfelt infatuation. This unrequited crush, witnessed by a mortified Kinjirou, leads her to behave in unusually feminine ways whenever Subaru is present, a sharp contrast to her normally rough-and-tumble demeanor. Her relationship with Kinjirou remains underpinned by a prickly but genuine sibling loyalty, while her connection to Subaru becomes the source of her most visible personal change: she moves from blunt hostility to a softer, more self-conscious version of herself. Though Kureha does not undergo a sweeping transformation, her arc reveals a hidden vulnerable side beneath the boisterous exterior, and her wrestling ability remains her most notable physical skill.