It's been half a year since her husband left home for work. Just as she was getting used to living with her son, Tohru, her mother, Shinobu, noticed that Tohru had been acting strangely recently. When Shinobu was taking a bath, she often sensed someone looking for a bra in the dressing room. Then one day, Tohru came into the bathroom where Shinobu was, even though she was taking a bath. "Mom... I can't take it anymore!" Tohru excitedly jumped on Shinobu's big breasts, squeezing them and starting to suck them.