Izumi has been single-handedly raising her son. Her son has successfully graduated from university and found a job. She thought that this would be the end of her child-rearing career, but... The company Kojiro joined was an extremely abusive company. There were practically no days off, and Kojiro's body and mind became increasingly worn out. Worried about Kojiro, Izumi lied and told him that his grandfather had died, and took him on a trip to a hot spring to cheer him up. On the trip, Izumi saw her son naked, and began to feel like a man.