Wato Chiyoko is a reoccurring character in the Osamu Tezuka Star System. She is a strong-willed, slightly tomboyish high school student who originally appears in the manga The Three-Eyed One. She has appeared several times in other Tezuka media.
Wato primarily goes by her last name, and is a very confident and outspoken teenage girl. Despite her size, she is quite strong and capable of winning a physical fight. In her original manga The Three-Eyed One, she hangs out with her classmate Sharaku Hosuke, whose forehead bandage conceals a third eye. She is one of the few people who know that exposing his third eye turns him into a demonic warlord, and helps guard this power with him. Quite often she was involved in fan service in the original manga.
In the Black Jack TV series, Wato and Sharaku appear together as brother and sister. Her name is adapted from "Watson", and Sharaku's full name is adapted from "Sherlock Holmes."