A housewife named Chika lives in a small apartment in Tokyo with her husband. A man named Kudo, who claims to be a salesman for health equipment, visits her. Deceived by Kudo's smooth talk, Chika signs an agreement to try out a massage machine for a week. This was Kudo's clever trap. He finds fault and demands payment of exorbitant purchase fees. Realizing she can't pay, he forces her into underground prostitution. But this is an extremely cruel form of prostitution where she has to perform lewd acts in front of her husband at home…
