Shihori Endo, a mother worried about her son who has no interest in the opposite sex even though he is of marriageable age. One day, she hears from her son that he has never masturbated. She regrets not having properly taught him sex education up until now, and decides to teach him how to masturbate herself. Her son is aroused by his mother's voluptuous large nipples. And Shiori is excited to see her son's erect penis for the first time... The loving and intense sex education between mother and son begins now...!