Visiting his wife's parents' home for the first time in a while, Sota finds himself flustered by his mother-in-law, Chisato's, alluring charm—a mature sensuality he doesn't see in his young wife. Wanting to cool his head, he heads alone to the bath, only for Chisato to suddenly appear and say, "Let me wash your back. You're my son now—don't be shy," gently lathering him up. Already tense inside, Sota is caught off guard by the intimate contact and involuntarily grows aroused. The warmth of her touch and the unexpected pleasure of being caressed begin to stir his emotions. It feels like time itself has shifted, wrapping him in something rare and forbidden. Slowly, he starts to recognize his own feelings—this relationship with his stepmother may be evolving into something entirely different.