One day, a man appeared before married woman Mio. He was the older brother of a man who had once casually used and discarded her. Blaming her for toying with his younger brother, he locks Mio inside a room and begins a hellish reign of abuse in the form of forced captivity and training. Trapped in a sexual nightmare where obedience is demanded, the humiliation and shame gradually transform into twisted pleasure, and Mio sinks deeper into becoming a true sex slave.