Mizuki is a happy nine-year-old girl living a normal life, though her grandparents constantly watch her with a strange sense of worry. Her ordinary world is disrupted when she stands up for a new student, Kizawa, against a bully. During the confrontation, Mizuki experiences a mysterious surge of power, causing her silver hair to flash with gold and allowing her to move with superhuman speed. This event marks the beginning of her friendship with Kizawa and makes her realize her grandparents' worry might actually be fear—fear of her.