Wife's Sexual Fantasy Before Husband's Eyes (1980)

Shûzaburô, a noble businessman has a sexual affair with a prostitute. But when he is in the bathroom, she is killed by two thugs. They blackmail him and making him accept to pay a large sum of money. He is offered two alternatives: to pay either 100.000 or 50.000 plus having sex with his wife, Saori. He chooses second alternative and gives them the the key of his house. So they viciously rape his sexy wife. But she becomes sexually aroused by the act of rape and wants more of same. But the husband finds out that this is all set up by her wife.