Pi-chan is a main character in the anime Nights with a Cat. She is the younger sister of Fuuta and a high school student who moves into Fuuta's household when she starts attending a school nearby. She is the owner of the Munchkin cat Kyuruga, and it is her arrival with the cat that brings the animal into her brother's everyday life. In appearance, she is a young woman with blonde or yellow hair that reaches chest length and black eyes.

In terms of personality, Pi-chan is warm, energetic, and openly affectionate, especially toward Kyuruga. She loves the cat deeply and eagerly tries to interact with him at every chance, whether by picking him up, playing with him, or attempting to sleep beside him. Her enthusiasm, however, is not always returned: Kyuruga tends to bite her when she holds him and runs away when she tries to share a bed with him, suggesting that the cat finds her attentions a bit overwhelming. She remains persistent and cheerful despite this, and her earnest but sometimes clumsy efforts to bond with the cat are a recurring source of comedy in the series.

Her main motivation is to be close to Kyuruga and to care for him as his owner, while her move to her brother's home is tied to her schooling. Within the story, she is one of the central household figures, and the everyday episodes often revolve around her interactions with the cat and her brother. Her key relationships are with Fuuta, with whom she shares a home, and with Kyuruga, whose cautious reactions contrast with the affection she gives. Across the anime's seasons she continues to appear as a main character, and her repeated attempts to win Kyuruga's trust show her gradually learning to understand the cat's temperament, even when things do not go as she hopes. She has no supernatural or extraordinary abilities; her distinguishing traits are her devotion as a pet owner and her persistent, good-natured approach to caring for Kyuruga and adapting to his behavior.