After losing her husband, Yui lives alone with her stepson. Worried about her reclusive son after his father's death, she continues to care for him—but this concern is merely a pretext. Even during her husband's lifetime, Yui and her stepson had been aware of each other as lovers. One day, the two go on a trip together. At a traditional inn, the son makes advances toward her. Though she resists, her heart swells with joy. She takes his cock into her mouth and passionately caresses her own secret area, her arousal spilling out in waves. Forbidden desires explode as they passionately crave each other in an intense story of incestuous lust. Their pure, profound emotions entwine, revealing the complex relationship between them.