One morning, Yukari watches her son Yutaka head to school while clutching his crotch, concerned by his appearance. Sensing something is off, she sneaks into his room the next morning. Just as she suspected, Yutaka is suffering from an abnormally large morning erection, tossing and turning in his sleep. "Your father was the same, so I never thought... but such severe morning wood..." she murmurs, unable to bear the sight of her son's distress. Unable to resist, she gently strokes his erection just as she used to do for her husband, softly licking the tip, sucking his balls, trying to calm his arousal without getting caught. But Yutaka, overwhelmed by the pleasure, pretends to be asleep, lost in sensation. The next day, he begs Yukari to relieve his morning wood, throwing himself at her—and a new, forbidden relationship begins.