"PENG" is about a woman entering her 30s as four different men become entangled in her life. 30-year-old Go Sa Ri who is trying to start fresh as she says goodbye to her 20s. She faces a difficult situation when her ex-boyfriend, a younger guy, her best friend, and her boss simultaneously try to win her over. Pi Jung Won, a talented media artist who also own his own gallery and cafe. He develops feelings for Go Sa Ri, who he has been close friends with since they were young. Ki Sun Jae, the CEO of the fashion brand that Go Sa Ri works for. A nearly perfect guy with both looks and skills, he shows warmth in his actions although he appears cold at times. Yeon Ha Rim, a younger guy who isn't afraid to express his feelings. Doo Ru Mi is a model who is always straightforward and confident, always willing to show interest when a handsome guy appears. She is an affectionate character who is very loyal to her friends.