Watcher Girl 2

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.
(Source: HanCinema)