Worried about her pregnant daughter, Rinka comes from the countryside to help the couple. Her support is supposed to ease the tension at home, but a conversation about masturbation only makes his wife angrier. Resenting that she alone must suffer during pregnancy, she forbids her husband from even touching himself. Days later, pent-up and frustrated, he accidentally sees Rinka naked after her bath. Noticing how unsettled he is, the concerned mother-in-law asks him to tell her everything, setting the stage for repeated breeding sex behind her daughter's back.