Mi-na enjoys rough sex and she's currently sex partners with Woo-yeong, who she met on a one-night-stand. Mi-na's best friend, Jeong-hee, coincidentally witnesses Mi-na having sex and opens up to a new world. One day, Jeong-hee is invited by Mi-na to watch her having sex with Woo-yeong...

Couple Hee-joo and Woo-seok, who are in good harmony with each other, become increasingly provocative sex addicts. Unknown to Hee-joo, Woo-seok offers watching sex to his senior Jong-gyu, and Jong-gyu gets a thrilling experience. After having a taste of "spectator sex" Jong-gyu secretly meets Hee-joo and his girlfriend Mi-seon and the three of them have sex.