Koyu Ohara – Shudojo: nure nawa zange AKA Wet and Rope (1979)
A young woman gets raped by three thugs on her wedding night while her husband is forced to watch. He then tell her to leave because his honor has been violated. She attempts to commit suicide, but a priest talks her out of it and she decides to become a nun. Once inside the convent, she is again a victim of sexual abuse.