After that, we went to another open-air hot spring and did it again. This open-air hot spring had no roof, and was separated from the next one only by a single wall, so we could even clearly hear the couple next door chatting and laughing.
So we could only try not to make any noise and do it secretly.
This girl's butt is really big and soft, it feels especially good to touch. I really wanted to slap her butt hard, but because there were people next to us, I had to hold back.
She also seemed particularly excited because she was doing it while listening to the voices next door talking, and she got extremely wet down there.