Kirie is described as having an extremely menacing aura, which leads her to having few friends. Kirie may have earned this reputation as aggressive when she started her classes, as she was seen hitting an older man (her brother) and since then several students have been afraid to get that close to Kirie without really knowing her. It's also implied that she is actually shy to the point that she can only talk to small children, as seen with Umaru's indoor mode, which has the appearance of a child. She calls Umaru's indoor mode (Komaru) as "Master" and is in service to her. When she is with Komaru, we see a facet of Kirie more beautiful and helpful because she serves her teacher Komaru since she met her although she is really Umaru. Her relationship with Komaru helps Kirie to be more social, open and to take a lot of confidence to be with Umaru and company, she even relates with Alex Tachibana and Taihei Doma, although at the beginning it costs her. However, she is often violent towards her brother, Takeshi Motoba, due to his occurrences and actions. Takeshi is always concerned about his sister's well-being despite his treatment of her and always tries to relate to Kirie to get back to his old relationship Kirie has written a story book for children, named Master and the Mysterious Fish. Kirie's storybook author's name is “Kirinrin”. Kirie has a "special ability" to remove all traces of her existence, becoming invisible. She has the skills of a pro swimmer, but gets quiet when people compliment her about it. Kirie wasn't allowed to ride a roller coaster because she didn't clear the height restriction of at least 140cm. She secretly has a crush on Umaru. She is possibly sapphic. In the manga, Kirie has a fear of dark place, especially forests "Hi...I'm kirie motoba."