Kyōko Tōno is a first-year high school student and the childhood friend of the protagonist, Shōichi Kamita. They have known each other since kindergarten and spent much of their early years playing together at a park located on top of a hill, a place that holds significant nostalgic value for both of them. Kyōko is an honor student who consistently earns excellent grades, yet she also has a strong fondness for shōjo manga and horror stories. She can behave in a playful, somewhat childish manner that contrasts with her studious image, and she is self-conscious about this duality, often worrying about the two sides of her personality. She is naturally bright, cheerful, and energetic, with a mischievous streak, but she is also caring and sensitive to the feelings of those close to her.

In the series, Kyōko serves as one of the main heroines in the omnibus structure, with her own four‑episode story arc that focuses on her relationship with Shōichi. Her arc explores her transition from a longtime friend into a romantic partner, as she grapples with her insecurities and the fear of changing the dynamic of their bond. Her academic discipline and involvement in the home economics club demonstrate her diligence and practical abilities, while her warm, outgoing nature makes her a comforting presence in the lives of her classmates. Over the course of her arc, she gains greater confidence in expressing her feelings and learns to embrace both her serious and playful sides, ultimately growing into a more self‑assured young woman.