Kotori Haruno is a 15-year-old high school student from Sapporo, Hokkaidō, who lives with her mother, Yoko. Her father is deceased, and due to Yoko's demanding work schedule, Kotori takes on the duty of managing their household.

She has a strong interest in cooking, a hobby she both enjoys and relies on to maintain the home while her mother is away. Kotori is also an active member of her school’s tennis club, where she participates with her best friend, Ayu Kawahara.

Her relationship with the protagonist begins with a sibling-like dynamic, though this may evolve into deeper emotions as their interactions progress.