Pinoko  

Peach, Penny, Pinoco, ピノコ

Pinoko is Black Jack's companion, a young girl constructed by him who has a rare type of Siamese twin living inside one of his patients for 18 years until she was extracted and given a real body with an exoskeleton. After being rejected by her sister, she lives with Black Jack in his house and helps with household chores and acts as an assistant during some operations. She often provides comic relief in the series, appearing to be around five years old but claiming to be eighteen and engaged to Black Jack, despite him treating her more like a daughter than a romantic interest.