Chitose Hibiya is the landlady of the Gabu Jougasaki apartment complex, where protagonist Hideki Motosuwa lives. She is a young woman of average height with long, dark lavender hair and dark purple eyes. Typically appearing calm and composed, she is often seen carrying a broom while maintaining the property. Her outward demeanor is consistently kind, patient, and friendly; she greets her tenants with a warm smile and offers help without judgment.

Beneath her ordinary exterior as a landlady, Chitose possesses a remarkable and secretive past. She was formerly a scientist who worked alongside her late husband, Ichiro Mihara, at Piffle Princess Enterprises, where she participated in the development of persocoms. Because she was unable to have biological children, her husband created two advanced persocoms named Freya and Elda, who would later be known as Chi, to serve as her daughters. In this sense, Chitose is considered the mother of Chi, viewing the persocom not as a machine but as her child.

Chitose's primary motivation throughout the story is to ensure Chi finds happiness and the person just for her, as her husband wished. She promised Ichiro that she would only observe Chi from a distance, a vow she respects for most of the narrative. However, she finds subtle ways to guide Chi, most notably by authoring a children's picture book series titled A City with No People, which uses allegory to teach Chi about love and relationships. Chitose also secretly provides Chi with many elaborate outfits, which are actually keepsakes from the time she lived with both of her persocom daughters. When Chi and Hideki face practical difficulties, such as Chi needing to learn how to bathe or losing power, Chitose discreetly offers assistance from her position as landlady.

Chitose has several key relationships that define her role. Her most significant bond is with Chi, whom she loves as a daughter but cannot openly embrace due to her promise to her husband. She also maintains a friendly relationship with Hideki, offering him advice and support, and she is revealed to be highly intelligent, once using her scientific knowledge to repair the persocom Sumomo. Beneath her apartment building is a secret high-technology room that she uses to monitor the city and observe Chi's progress from afar.

In terms of development, Chitose is a static character whose strength lies in her steadfast resolve. Her journey is not about personal change but about maintaining her silent, watchful role as a mother who sacrifices being known by her child in order to give that child a chance at true love. She has the ability to deactivate Chi if necessary, demonstrating the heavy responsibility she carries as her creator, but her goal is always to see Chi succeed. Her notable abilities include extensive knowledge of persocom engineering and programming, allowing her to repair and understand advanced technology that others cannot.