As a cat, Katy is black and white with a cute, basically upside down bow on her head, with little black eyes. As a human girl, she wears plain red slippers, the same bow and a knee length, turtleneck pink dress with long sleeves, and a white apron. Her eyes are green, and her hair is bluish black.
Katy is both a cat and a human! She really is a cat who was abandoned by her family (human family probably). She dreams of becoming a witch so she can do whatever she wants to people who are mean to her. Unico meets her and they become friends. The two of them float down a river in a basket until they come to a forest with a cottage that an old woman lives in. Katy is convinced that the old woman is a witch, but is apparently not. Katy then decides that if she's to be a witch, she has to be a human girl first (since a kitty witch might look funny). Unico grants Katy's wish because they're such good friends and Katy turns into a human girl. Katy thinks that the Old Woman changed her and thanks her by helping her out around the house. However, Katy grows tired of her chores and wanders off to a field to do nothing. Unico finds her and tell her she should do her work because the Old Woman is very old and fragile. Katy refuses, and Unico tells her that he changed her, not the woman. Katy doesn't believe him, so Unico changes her back to a cat. Katy then wanders around the cottage as a cat again and then realizes that the Old Woman really does need help and that she's really lonely. Katy tries to help out as a cat, but just gets in the way, and becomes very sad about it. When the Old Woman falls into the creek while washing clothes, Katy dives in to save her. While she's diving, she changes back into a human girl and she rescues the Old Woman. From then on Katy is a better person, but soon gets in trouble again when she meets Baron DeGhost.
