Kozue Matsumoto is a classmate and eventual girlfriend of Baki Hanma. She is the daughter of Kinuyo Matsumoto, who serves as Baki's landlady, and her father was a fighter who lost his life in the underground arena. Kozue is a gentle and caring individual who becomes deeply attached to Baki, though she initially denies her feelings when asked. Witnessing the savage world of underground fighting leaves her troubled and disillusioned, and she repeatedly pleads with Baki to leave that life behind. Despite her ongoing discomfort, her perspective shifts after she visits the grave of Baki's mother, Emi, which allows her to better comprehend his unwavering determination. Her personality is defined by kindness, loyalty, and emotional fortitude, as she remains a non-combatant amidst extreme violence. Her primary motivation is Baki's safety and well-being, and she longs to offer him a sense of normalcy and unconditional love. Within the story, she functions as Baki's central love interest and emotional anchor, the person who connects him to a world beyond combat. Their relationship deepens over time, culminating in an intimate moment before his fight with Yanagi that symbolically marks his passage into full adulthood. Kozue's development takes her from a schoolgirl who hides her affection to a committed partner who accepts the reality of his path, even as the narrative often shifts its focus to the ring. Her notable ability is not physical combat but the steady emotional support, resilience, and loyalty she provides, enduring the constant fear of losing someone she loves while remaining a steadfast presence in his life.