Koatsu had gradually come to love his mother purely as a woman. Wanting to confess his feelings, he decides to invite her on a hot spring trip. Finally gathering his courage to confess, his mother responds by surrendering her body, saying "Only kissing is allowed." But for Koatsu, who harbors pure love, kissing alone is not enough. He passionately takes his mother outdoors, and at the hot spring inn, they desperately crave each other. Mother Yuko enjoys the situation, yet her emotions waver between guilt and satisfaction.