The Adolescent (1967)

A 13-year-old girl in Tokyo, just beginning to realize her own sexuality, comes home one day and finds her mother having sex with her boyfriend. She gets enormously upset by the incident. Then she is sent to her aunt, who will take over the upbringing of the girl. When she arrives at her aunt's house in the country, she discovers that her aunt and cousin are not quite what she thought they were. Before she reaches the house, she is raped by Katsuo, her female cousin's boyfriend. Then she starts relationship with Katsuo, which leads to terrible tensions within the family and she gets into trouble with her aunt and cousin.