The inside of a kotatsu is vague, but it's erotic, right? When invisible parts of the skin touch each other, the imagination runs wild because you can't see it, and it stirs up sexual desire. Moreover, the situation is that the girl's boyfriend is right next to her! This is erotic. The sight of her dripping so much love juice in the kotatsu that you can hear the sounds without her boyfriend noticing is a must-see!
