Female Prisoner 701: Scorpion (1972) on Netflix

Plot summary

Nami Matsushima falls for Sugimi, a police detective, and does the work he asks of her: she goes among a drug smuggling ring on his behalf. When the dealers discover her, they rape her, and she learns that Sugimi was using her to get a bribe from the yakuza. She goes after him with a knife on the steps of police headquarters and fails. A court sends her to a women's prison, where she is known as number 701. The guards are sadistic, and the inmates include Yuki Kida, Otsuka and Katagiri. Outside the walls, Sugimi and his mob connections begin arranging what they intend to look like an accident inside the prison.