Chise Mihara is the older of the twin daughters of Chitose Mihara, the kind and generous landlady of the apartment complex where the protagonist, Hanato Kobato, resides. She lives with her mother, her father, and her younger twin sister, Chiho Mihara. Chise and her sister are recognizable by their long blonde hair, which reaches their knees, and their brown eyes; Chise typically wears dresses with a black background and white details, and her headband color helps distinguish her from her sister.

Chise is portrayed as a cheerful and curious child who shares her sister’s fondness for animals. Her youthful curiosity and compassion are demonstrated when she and Chiho help Kobato find a new owner for an abandoned kitten. Although they are relieved the kitten finds a home, they remain worried about its well-being. Chise is soothed by Kobato’s song, which heals her heart and provides a moment of comfort.

Within the story, Chise and her sister are minor supporting characters who add warmth to the everyday setting of the Mihara household. Their primary role is to be kind and playful children who interact with Kobato, contributing to the series’ gentle atmosphere. Chise shares a close and happy relationship with her mother, Chitose, and her sister, Chiho, with whom she is almost always seen.

Chise is a significant and intentional visual callback for fans of CLAMP's earlier work, Chobits. She and her sister are designed to look exactly like the persocons (personal computers) Freya and Elda from that series, with the only differences being their human ears and more expressive emotions. Unlike the tragic fate of their counterparts in Chobits, Chise and Chiho are ordinary human girls living a joyful life with both their parents. She does not possess any notable supernatural abilities.