Wato is a self-confident, tomboyish and somewhat violent high school girl. Her principal role is in The Three Eyed One where she is Sharaku’s friend and keeper, and the only person who has the power to put on and take off the bandage which seals his third eye, and his evil powers. In the Black Jack TV series, she is Sharaku's elder sister, constantly nagging him to be more self-confident, and to do his homework.