As soon as I was about to go home from school, it started raining. I had no choice but to wait for the rain to subside and headed to the classroom. I thought no one else was there, but Kisaki-san, a very serious person in the class, was there. She says she is waiting for the rain to stop just like me. It was supposed to just be the two of us waiting... That serious girl suddenly showed me her tongue and even her panties as if to provoke me. She teases me, a virgin, and her behavior gradually escalates...