Yuko's younger brother Atsushi and his wife Naomi are suddenly transferred and forced to stay at the Shiraki household for a while. Initially welcoming, Yuko becomes increasingly frustrated seeing the couple's affectionate relationship and her own sexless marriage. Her pent-up desires grow stronger each day until she finally sneaks into Atsushi's bedroom. Though shocked at first, Atsushi cannot resist Yuko's aggressive seduction and gives in to his lust. From that night on, Atsushi becomes nothing more than a tool to satisfy Yuko's insatiable appetite for sex. His life is now pulled into a new world of chaos and overwhelming desire.