After the massive success of The Street Fighter, the Toei Company decided to build a new karate series around a female lead, and cast a young actress who had appeared in a cameo role alongside her mentor Sonny Chiba. Still a teenager at the time, Etsuko Shihomi exploded onscreen in her first leading role and created a new character type: a tough fighter who was fierce, fearless, good-hearted, and decidedly non-sexualized, a departure from Toeis typical formula.

In 1974s Sister Street Fighter, Shihomi is the half-Chinese, half-Japanese Li Koryu, who travels to Yokohama to investigate the disappearance of her brother, an undercover cop. Li discovers a smuggling ring run by a drug lord with his own personal army of deadly fighters, and must penetrate his evil lair with the help of a fellow karate master (played by Chiba). Shihomi and director Kazuhiko Yamaguchi (Wolf Guy) made two additional films based on the same character over the next year, Si