Umaru Doma is a high school girl who, despite having a refined appearance in public, acts like a total slob at home, much to the dismay of her older brother, Taihei, who she constantly barks orders at. Wanting to win an online contest, Umaru tries to teach some tricks to her pet hamsters. Later, after spending the day with her worriesome classmate, Nana Ebina, Umaru has an intense snacking session, only to wind up becoming too full to eat her favorite meal. Afterwards, Umaru gets angry at Taihei from pulling away from a gaming session with her in order to buy the weekly groceries.