The original source material is a fantasy-mystery rom-com webtoon that was released from May 2015 to June 2016, with a time-slip element (this is probably the fifty-bajillionth one so far). A man named Shin Woo regrets letting his first love go ten years ago because he didn’t have the courage to confess. However, he gets the chance to win her again when he travels back in time, and this time he’s armed with the knowledge that she liked him back then too. Unfortunately, he has a pretty strong competitor: himself from ten years ago. The present Shin Woo and the past Shin-woo engage in a fierce (and probably funny) rivalry to win their love’s heart.