Onna hissatsu ken (1974)

Lee Long is a martial-arts champion who the police use as an undercover agent to infiltrate a drug ring responsible for importing heroin from Japan to Hong Kong. When he is identified and imprisoned, the police pressure his sister, Tina Long, to help them locate and free him. She gets the help of Lee's martial-arts school, including the powerful Sonny Kawasaka, for the inevitable battle-royale with the drug gang, which includes masters of many different 'schools' of fighting.