"Shirakami-san! We're going to get caught!!" "It's fine... Just put it in already." I never imagined my life would take such an extraordinary turn... --- One day during class, I was staring blankly at Shirakami-san from the seat behind her. She's quiet and reserved, but cute. As I was thinking about how cute she looks from behind, she started moving strangely. She's masturbating! She's groping her crotch with her hand!! And on her desk, hidden by a textbook, was her smartphone, with a huge cock filling the entire screen! The serious Shirakami-san, masturbating during class... Before I knew it, I started jerking off using her as my fantasy. I jerked off frantically and came. My underwear got dirty. When I happened to look forward, Shirakami-san was looking back at me. Our eyes met. Shit... did she see me...? The end-of-day bell rang, and Shirakami-san approached me. "Come to the empty classroom on the 3rd floor later, okay?" My heart was pounding at this unexpected turn of events as I headed there... And there she was, Shirakami-san, wearing see-through, incredibly erotic lingerie. Forgetting that we were at school, I was beyond excited and devoured her. The most thrilling school sex life between Shirakami-san and me had begun.