20-year-old Kyeong-soo is a man who's full of assumptions. He learned about sex from Internet porn, but nothing about the real thing. He's only had crushes and has never even kissed before. He got embarrassed when he confessed his feelings to Ji-yeon, his crush. He comforted himself from the shame with Japanese girls in his room with his right hand. One day, he has a fight with his father and remembers his friend Baek-hyeon had invited him over to Gangwon-do. Is she a vampire? His friend's mom Hyeon-ok never ages! She's good looking enough to look in her 20s. Then one day, she spends a lonely night drinking on the beach and her son's friend starts to hit on her. Should she accept or not? Is it love or a fling? Kyeong-soo is able to have sex several times a day. They do it at home, on the beach, in the water and again and again; he's hard again. Hyeon-ok thinks Kyeong-soo is cute; however, when his crush Ji-yeon comes down, Kyeong-soo starts to get confused. Does he love Hyeon-ok or was it just a fling?