Due to talk of his parents' divorce, Hiromasa ends up staying with his uncle and aunt... His aunt Reiko's caring and slightly excessive physical contact makes him feel excited in his crotch. One day, Hiromasa spends a sleepless night hearing the sounds of his uncle and aunt's lovemaking coming from their room. A few days later, he pretends nothing happened, but Reiko provokes him with an indecent appearance, and to his surprise, her lewd behavior gets him excited and he starts playing with his erect penis with a smile...