The title character, Maruko is a third-grade student raised in a relatively poor family of six. She is lazy, disorganized and usually late for school, in strong contrast with her neat, calm and tidy [older sister](https://anilist.co/character/39490/Sakura-Sakiko) (sixth-grader) who must share her room with her. Maruko, like many kids, tries to avoid homework and chores, and she takes advantage of her doting [grandfather](https://anilist.co/character/230184/Sakura-Tomozou) and squabbles with her sister. Nevertheless, she is a well-meaning child who tries to do good.