I went on a hot spring trip with relatives, and there in front of me was the chest of my cousin who had grown into a bombshell. While we were all washing together, my cousin saw my erect penis and got excited. Pretending to wash, I accidentally grabbed her voluptuous breasts. We ended up alone in the open-air bath, and naturally, we continued touching each other. Taking advantage of no one coming, she licked my penis in the bath and washing area, and we even secretly had sex.