Tsumugi is having a mistress. Because the two of them have families, they don't see each other often. Because they wanted to spend the whole day together, the two booked a room at a hot spring inn. And that day, when they got off the car and checked in, the two of them couldn't hold back anymore and rushed to enjoy each other's bodies. Long-suppressed desires are released, successive waves of sperm are shot deep into Tsumugi's uterus...