My stepmother, older sister, and younger sister, who became my family when my father remarried, are all naturists and always naked... but they started wearing clothes at home to be considerate of me, who was a high school student. Then, my panties and breasts, which had been so visible up until then that they weren't sexy, started to be panty shots and chest shots, and the little glimpses I could see were strangely sexy, and I got my first erection in my life! Since then, my head has been full of panty shots... I felt like I was going crazy, so I shut myself in my room, but my worried family came over and showed me their panties in front of me, and I got an erection...