Ryo, a mother, has been raising her only son, Makoto, on her own since her separation from her husband. - Ryo gives Makoto an excessive amount of education with an eye on her future, just as her ex-husband, who was struggling financially, became her teacher. - However, as Makoto grows older, he gradually becomes tormented by sexual desire and loses focus on his studies. - Ryo thinks about his son's future and lets him get rid of his desire with oral sex, even though he knows it is taboo. - However, this act also ignites Ryo's hidden desire. - The sex education escalates and goes beyond learning about the mechanics of a woman's body, to the feel of the female genitals and even intense real acts...