A refined married woman, Yoriko, accepts a ring to try out from a man who calls himself a jeweler. However, the ring is tampered with and Yoriko accidentally breaks it. Unable to resist the man who demands compensation, she is drawn into the underground sex industry... In her room at home where her husband is present, she opens her body to an obsessive customer, who inserts his raw meat rod and pours thick semen into her virgin vagina. As a series of acts that destroy all ethics, Yoriko eventually discovers masochism and awakens to the heights of agony...