One day in the cold winter, I was lucky enough to win a kotatsu at the lottery! As soon as I put it in my room, my older sisters, who usually don't come to my room, were attracted by the magic of the kotatsu and began to stay in my room. While I was looking at the lower bodies of my older sisters who became defenseless in such a "kotatsu", I inadvertently got an erection. Secretly inserting Ji-Po into my sister's mako illuminated by infrared rays! I received every single warmly hot mako!