Hiroaki lives with his wife Reiko.
One day, while they make love he calls her "Mamayu", which happens to be the idol he likes since very long time.
Unfortunately, it did not please his wife.
The next day, Taniguchi, an old friend from high school time is invited to celebrate their housewarming celebration.

Later in the evening, Hiroaki, after much drinking goes to bed and leaves his wife with his friend...