In the Kawaguchi household, sex education goes beyond mere knowledge transfer—it's taught through firsthand experience. To raise her son properly, the mother has resolved to fully expose herself. The family follows a bold educational approach: letting the son witness the intimate sexual relationship between husband and wife. Through this, she carefully explains to her son how sexual intercourse with a loved one is an essential step toward conceiving a child. In this way, they practice true sex education in its deepest sense.