The heiress of the Umenomori family and one of the main characters. Even though her family is wealthy, she is isolated by its prominence and her parents' absence. Her parents are normally busy at work and almost never around. It has been a little over a year since she last saw them, so she lives through every single day without feeling the warmth of a family. Thus, Chise is spiritually and emotionally orphaned, yet another "stray cat" in need of a home. She is a typical spoiled rich girl who uses her great wealth and authority to get whatever she wants.
She has the appearance of an elementary school girl, but is actually a high schooler the same age as Fumino and Takumi. She looks upon Takumi as her servant and has a strange desire for him to let her hold his hand as well as to pat on her head. She has a clash of personalities with Fumino, and the two girls end up bickering whenever they are within the vicinity of each other, usually requiring Takumi to intervene and put an end to the disagreement. However, as the story progressed, their endless bickering gradually became a sign of closer friendship.
She harbours a crush on Takumi because he was the first person to act totally oblivious to her status as the heir to the Umenomori family and to treat her normally. This, coupled with her loneliness, caused her to have a secret desire to join Takumi's circle of friends although she feels that a reason is required so as not to appear too abrupt.
To get around this problem, she decides to create a club and forcefully ropes in Takumi and his friends as members. When Takumi mentioned his afterschool job, she offers to buy every cake at the Stray Cats, hoping that Takumi and his friends can attend the club and keep her company. Takumi later refuses to sell her any cakes, telling her that it is meaningless to sell cakes like that and persuades her to try her hand at making a cake so as to understand why. Chise ends up making a passable attempt at baking a cake and subsequently decides to start working at the Stray Cats while Takumi and his friends also join her club. Later the club was named Stray Cats Associates Club (迷い猫同好会Mayoi Neko Dōkō Kai?), whose primary purpose is to help others in need. Compared to Fumino and Nozomi, Chise is much more open with her feelings for Takumi and would go through far greater lengths just to be with Takumi, much to the ire of Fumino.
She is often seen with her two maids and an elderly butler who deeply care for her.