In the working-class district of Osaka, the Kubo family is navigating life after the sudden death of the father. The cheerful and hardworking mother, Fusako, who works at a hospital during the day and runs a night club in the evening, is left to raise their three sons on her own. Before the traditional forty-nine day mourning period is complete, a mysterious man named Takanori appears, claiming to be the deceased husband's younger brother, and Fusako casually invites him to move in with them, beginning an unconventional family life.

Each of the three Kubo brothers is facing a distinct personal crisis. The eldest son, Masashi, is a quiet and mature ninth-grader who falls in love with a troubled older woman named Yuka. To get close to her, he pretends to be a college student and indulges her peculiar desire to find a father figure. The middle son, Yukio, is a violent thug who bullies others and is prone to fighting. When a classmate compares him to Hamlet, he initially believes it is an insult referencing a pet hamster. After learning about Shakespeare's prince, he becomes fascinated by the story, but it only deepens his anger and anxiety as he begins to suspect that his biological parents might not be who he thinks they are. The youngest son, Hiroki, is a grade schooler who, when asked about his future dreams, honestly declares that he wants to become a girl. He finds a kindred spirit in his sickly aunt Aki, who is hospitalized with cancer, and spends time with her role-playing and dressing up in costumes.

As the story unfolds, each character attempts to find their place by pretending to be something they are not. Masashi plays the role of an adult and a father figure for his love interest, while Yukio struggles to maintain his tough-guy facade as he grapples with his family history. A school production of Cinderella provides Hiroki with an opportunity to be true to himself, as his classmates unanimously decide he is the best choice to play the lead role, facing ridicule from some audience members as a result. Through these experiences of role-play, hidden identities, and spiritual visitations from the past, the members of the Kubo family ultimately learn to accept their lives and follow their own paths.