Trouble in paradise

In a small town in south korea women started to die and they concluded that there was a serial killer in the town. In this same town, a girl, abandoned by her parents because of her choice of career, meets her old neighbour, and her first crush. He remembered her and they start meeting again, but there was times when she had the feeling of constantly being watch, soon they started dating, everyone appreciated him except from one of her friends. He thought that the guy seemed too obsessed with her and could cause her harm, but she couldn't care less. But as days passed she started to notice everything, his unhealthy attachment to her, and she started feeling paranoid, about being watch constantly.