Nami Matsushima is used as a spy by her first real boyfriend, a police detective named Sugimi, to investigate a drug smuggling ring. However, her role is discovered and she is raped by several drug dealers. It emerges that Sugimi was simply using Matsushima as a pretext to obtain a bribe from the Yakuza. Seeking revenge, Matsushima makes a failed attempt to stab Sugimi on the steps of the Tokyo Metropolitan Police headquarters. She is sentenced to do hard time in a women’s prison, where she is given the number 701.