The mother and sister, who lost their husbands early and are in agony, are widows, but are still in the prime of their sexual lives. Masao, her stepson, is in love with her. At the end of winter, the mother, aunt, and stepson go on a trip to Naraijuku for some reason, where they meet local men and have sexual experiences with them, and are kidnapped and raped. At the final inn on the journey, the stepson has his first sexual experience with his mother, whom he has always admired, and so begins his journey of sexual adolescence.