MKON-025 I'm really sorry ... Sachiko was played to promise by her classmates that she would rub her sister's boobs

I promised my friend to rub my sister's boobs ... When I told my sister about it, she said, "... good." To be honest, I thought I would be refused, and I was shocked by my sister who had no idea of chastity. Because you can't let someone you don't know rub your boobs! I didn't seem to have a boyfriend until now, but I wonder if it was actually a bitch. That's why the classmates came to us. From now on, your sister will be rubbing her boobs ...