Shôjo abareru (1980)

A 15-year-old girl lives in a base town in the Kanto region. She doesn't go to school and earns pocket money by prostituting herself with her delinquent girl group friends, living day to day. However, one day she gets fed up with the small size of her town and goes out alone to Shinjuku Kabukicho. At night, she is accosted by drunk men and nearly assaulted, but is rescued by a man. The man is an undercover detective on patrol. Thus begins their strange life together.