Hyeon-goo, who always dreamed of a threesome, carefully talks about it to his girlfriend, Mi-na, but ends up in a big fight. After hearing this, Seung-mo goes to see Mi-na, and Seung-mo’s sex partner So-hee approaches Hyeon-goo… Then one day, Seung-mo calls Hyeon-goo and asks him to come quickly. Hyeon-goo goes to Seung-mo’s house and sees two people wearing only underwear.