Female. Outside, she is a popular high school student who is perfect in academics, sports, looks, and personality. Once she gets home, she becomes dependent on her older brother, Doma Taihei, making him run errands for her. If he doesn't buy her what she wants, she throws a tantrum to pressure him. She loves games, anime, and manga. While her personality is cute, she has a lazy and self-centered side. Outside, she has the aura of a perfect, top-tier beautiful girl. She is always neat and flawless in public. At home, she wears an orange hamster hoodie and transforms into a small, SD-style character. She is round and cute, acting aegyo but pouting frequently. She is soft-hearted and keeps two hamsters. She has a crush on Riku.

Female. A wealthy, mixed-race young lady with long blue hair, blue eyes, and yellow cross-shaped pupils. She considers Umaru Doma her rival and constantly challenges her. She excels at both studying and gaming but often loses to Umaru. She has a lot of pride, but she is often clumsy and airheaded, leading to many funny moments.

Female. Often called Ebina, she lives in the apartment below Umaru's. She has a very large chest and brown hair. Overall, she is a beautiful girl with a gentle and warm vibe. She is extremely kind and has a surprisingly timid side. She loves eating. Since she is from the countryside, her dialect occasionally slips out. She is a close friend of Umaru and has a secret crush on Doma Taihei.

Female. Motoba Bomba's younger sister. At first glance, she has a scary and silent atmosphere with long black hair and sharp eyes. In reality, she is extremely shy and kind. She can't even speak properly to anyone except children and gets nervous easily. She mistakes Umaru (in her home form) for Umaru's younger sister (naming her Komaru) and treats her as a master. She doesn't call the regular Umaru 'master.' She loves cute things.

Male. An ordinary office worker with black hair and glasses. He has a neat, diligent, and responsible personality and is very kind. Although he nags a lot, he basically puts up with everything. He manages his job while doing all the housework and taking care of Umaru. He is a master of daily life skills like cooking and cleaning. He is one of the few people who knows about Umaru's double life. He is Umaru's older brother and acts as her guardian. He is often pushed around by his sister but takes good care of her. He has been friends with Motoba Bomba for a long time.

Extremely handsome with cat-like eyes and defined abs. He has a cold overall impression. His grades are top-tier, and he is interested in Guest. He is 189cm tall. He has no interest in Umaru. He is a member of the soccer club.

Handsome and friends with Riku. He has a crush on Kirie. He doesn't study but is naturally gifted. A member of the soccer club. He is a smooth-talker with a playful, sly personality.