To her classmates, Umaru Doma appears to be the perfect girl. She's beautiful, friendly, and fashionable, earns top grades, and seems to be able to do any task asked of her with ease. She's even humble and polite! However, if Umaru's classmates could see her in the privacy of her home, they wouldn't even recognize her. Once she's inside the door, the pretty clothes come off, the orange hamster hood goes on, and it's time to pig-out on snack foods, binge-watch television, and play violent video games! This version of Umaru is everything that the public Umaru isn't: she whines, rolls on the floor, leaves messes all over the apartment, and makes life miserable for her poor older brother, Taihei. Even the most guarded secrets have a way of being found out, and, as Umaru becomes even more obnoxious and outrageous, her two lives are bound to collide in disastrous fashion in HIMOUTO! UMARU-CHAN!