After the massive success of 'The Street Fighter', Toei 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 Toei's typical formula. The film was another huge hit for the studio and Shihomi and director Kazuhiko Yamaguchi, who had previously launched Meiko Kaji's career at Toei, made two additional films based on the same character, with a final unrelated follow-up appearing a year later. In 1974's 'Sister Street Fighter', Shihomi is the half-Chinese, half-Japanese Koryu Lee, who travels to Yokohama to investigate the disappearance of her brother, an undercover cop. When she discovers a smuggling ring run by a drug lord with his own personal army of deadly fighters, she must penetrate his evil lair and defeat not only his champion (Masashi Ishibashi from the Street Fighter films) but also a group of female Thai kickboxers called The Amazon Seven. Chiba appears in a cameo as a fellow karate master who helps Koryu in her mission.