縄で犯す (1980)

Satoko, a mentally frail girl, is taken in by Anzai, the owner of a hot springs inn, after her parents commit suicide. One day, the clerk Matsuo forcibly takes Satoko's virginity. The following night, the clerk appears in Satoko's room again. The servant Shozo feels sorry for Satoko and invites her to run away to Tokyo with him. Meanwhile, Shozo steals money from the inn and accidentally kills Matsuo. He buries the body and runs away to Tokyo. Satoko is left alone and is subjected to Anzai's bizarre torture...