Sumire, a married female teacher whose husband's way of thinking is beginning to differ from hers, ends up sharing a room with the vice principal at a preparatory school trip. She is attacked while sleeping and resists, but she soon falls for the middle-aged man's persistent techniques. Over the course of two days and one night... the married woman's Kokoro after the trip... The 13th installment of the profound immorality series that can never be shown to her students or husband.