Jiro's mother is a supporting character who appears early in the story. She resides with her family, including her son Jiro and daughter Kayo. When Jiro returns home with scratches after defending a classmate from bullies, she remarks that he looks heroic. However, in the same moment, she gently reminds her son that fighting is never justified, a statement that reflects a pacifist worldview and an effort to instill moral values in her child. Her personality appears calm and nurturing, offering a balanced perspective that acknowledges courage while also teaching restraint.

Her role in the narrative is brief, serving primarily to establish the ethical foundation of Jiro's upbringing. The character's other personal background and motivations are not explored within the film, and her name is not given. As a result, her development is static, as she does not undergo any change or appear in later stages of the protagonist's life. No notable abilities or unique skills are associated with the character. She exists as a figure from Jiro's childhood whose influence is conveyed through a single, memorable piece of advice about the nature of conflict.