Fuyuhiko had a strange habit. When his father leaves home on a business trip, he peeks into his mother Ayumi's bath. Her mother, who actually knew about such a son, called out to Fuyuhiko, who was looking into her as usual, "Let's go in together." Fuyuhiko was bewildered by the sudden turn of events, but after that day, the bathroom became a forbidden place for the two of them.
