One day, when Reiko returned home from shopping, she found her husband's stepchild, Ataru, looking depressed in his room. Worried, Reiko spoke to him and learned that Ataru was worried about sex. Reiko was happy that her son, who had not opened up to Kokoro for two years after being married to her husband, had finally confessed his troubles to her for the first time. Wanting to help in some way, she used her huge breasts to teach Ataru about sex...