Mikiko is married to a man who runs a construction company, but is sexually frustrated and has an affair with one of her husband's subordinates. One day, while she is obsessed with sex, her secret is discovered by her husband's stepson, Toshihiko. Taking advantage of her weakness, Mikiko is pressured to "do whatever he says." She refuses and begs, but with nowhere to run, she finally takes her stepson's penis in her mouth. Called a "sex slave," Mikiko gradually loses her reason as she is relentlessly violated...