Dai, who is ignorant about sex, spends his days in agony, not knowing how to release his erect penis. At such times, he takes the plunge and consults his friend's mother, Momoko, who always treats him kindly... Momoko is confused when she learns about his troubles, but she secretly teaches him how to have sex. Then, Dai, who was overcome with excitement and pleasure from her for the first time, pushed Momoko down with all his strength.