After having a child during her university days and raising him as a single mother, Kaede's son has now become a college student. Kaede takes her son on a hot springs trip. While Kaede is happy to see her son grow up, he has something important to tell her during the trip. Her son has developed feelings for her as a woman. Confessing his love, the son pressures Kaede. Giving in to his primal instincts, he takes her. Kaede initially resists but eventually surrenders to the pleasure, promising just one night together. They engage in forbidden incestuous sex throughout their hot springs trip.
