Koma Oketani is the young cat living with Yuzuko Oketani at Third Street's Matsunoyu bathhouse. As the bathhouse cat, she helps welcome guests, comfortable with its daily rhythms. Constant exposure to water here overcomes any natural feline dislike, and she sometimes borrows bathhouse toys for play.

Her styled white fur features darker patches above her eyes, pink inner ears, and striking purple eyes. She typically wears black and white clothing.

Koma blends lively, playful kitten curiosity with moments of timidity. She enjoys chasing things and acts impulsively, like eating from a stranger's bowl without a second thought—a habit that once led her and Momo into trouble with a new dog. An unintentional ear twitch betrays her lies. Despite her youth and occasional fears, she dislikes being seen as a baby and actively seeks challenges, often joining Tora's adventures to prove herself.

She shares close bonds within the Third Street group, especially with Momo Hanasaki; they spend significant time together, collaborating on tasks like searching for missing Tama. Koma frequently interacts with Tora, viewing him as an adventurous role model despite their playful teasing. Her interactions with the intelligent stray Nora reveal a secret admiration; she consistently invites him to group gatherings and values his presence.

During Tama's disappearance, Koma actively joined the search. She informed Momo and accompanied her through the neighborhood, including investigating a new resident's property. This led to the encounter with the unfamiliar dog after she sampled its food. Her birthdate is August 13th. No concrete background information exists beyond the 2020 "Uchitama?!" series.