Observing the panty shots of a friend brought by my sister under the kotatsu and having raw sex with her

My sister's schoolgirl friends (Yuzu Shirasaki, Airi Natsume, and others) are studying under the kotatsu and secretly peek inside the kotatsu and observe her panty shots.They find out that she has an erection, but she's in heat. Since I touched his dick, we licked each other with finger cunnilingus and blowjob so that he wouldn't find out, and then we enjoyed raw sex