Ra Eun Ho (Kim Sejeong) and Hyun Tae Woon (Kim Jung Hyun) have been steadily evolving from friends to something more. As friends, they fought incessantly, but always cared for each other in the end.
The start to their love story was simple and innocent. When Eun Ho was falsely accused of being Suspect X, Tae Woon spoke coldly to her, but left her favorite lemonade for her. In order to exonerate herself, Eun Ho tried to find out who Suspect X was. While comparing Tae Woon’s lips to the one in the composite sketch, Tae Woon joked, “Isn’t your heart fluttering?”
While Tae Woon seemed to have the edge in their romance in the beginning, tables turned when he revealed himself that he was Suspect X. There were instances when Eun Ho’s face would be close to Tae Woon’s and he would seem embarrassed, escaping the situation immediately. Contrary to his normal personality, he has been showing a cute and charming side of himself.
Eun Ho and Tae Woon became even closer after Tae Woon revealed that he was Suspect X. Eun Ho then discovered that Tae Woon had continued his activities as Suspect X in order to protect her. They bonded by going to see the night scenery, and started caring for each other on a deeper level.