"It's cold, so bring out the kotatsu." My sister's friend came to visit, but the heating in the house broke, so I decided to lend her the kotatsu. She told me to adjust the temperature because it was too hot, so I crawled inside, and both my sister and her friend spread their legs wide open, exposing their panties. They were also wet with sweat. I couldn't help but get a full erection. My sister's friend found it amusing and started playing with my dick...