Kumiko Honma is a supporting character in the anime Black Jack. She is a high school teenager with shoulder-length brown hair and brown eyes, often seen in her school uniform or the waitress outfit she wears while working at Tom's Coffee Shop, the café that Black Jack frequents. She is the daughter of the late Dr. Jotaro Honma, the doctor who saved Black Jack's life when he was a child. Because of that bond, Black Jack feels a profound sense of guardianship toward her, regarding her as a younger sister and quietly looking after her without her knowledge.

In the original manga, her name is Kumi Yamashita, and she is an eighteen-year-old who was once engaged to Shoichi Maruguri. The engagement ended after she developed Cushing's syndrome, prompting Shoichi to abandon her. Black Jack cured her illness and later defended her when Shoichi tried to return. During that time, Kumiko fell in love with Black Jack without recognizing him, as she could not recall his face.

Kumiko moved from China to Japan to attend Oana Senior High School under the care of Tetsu, a former patient of her father who felt indebted to the Honma family. Her life is ordinary and grounded, revolving around school and her part-time job, which places her at the periphery of Black Jack's world. Although she carries a meaningful emotional connection to the protagonist without realizing it, she remains largely unaware of the protective role he plays in her life.