EQ-440 Playing tricks secretly in the kotatsu, "Wait!? My boyfriend will notice!" Having genuine sex with my boyfriend's friend!

He visits his girlfriend's home with a friend. It is winter. There is a kotatsu in the living room. For various reasons, they end up drinking together. Eventually, whether he passes out or gets passed out, her boyfriend ends up drunk and asleep. Driven by alcohol and the eroticism of the kotatsu, his friend's imagination runs wild with desire. He plays a prank on the woman he shouldn't touch, all while feeling tense with her boyfriend sleeping right next to her.