Nao Kato is a full-time housewife living with her husband and son. She married her husband, who was her senior in college, after unexpectedly reuniting at the company where she started working, and they quickly fell in love and tied the knot. Together, they raised their son. However, one day while cleaning her son's room, she discovered her own underwear hidden beneath his pillow. It turned out he had started masturbating using her undergarments. This habit continued to grow, and when she tried to discipline him, she was shocked by how hot, hard, and intensely responsive his penis became.