Five years ago, academy teacher Song Yeodan looked out for troubled student Yun Jaewon. But when Jaewon began mistaking that concern for something more, Yeodan knew he had to draw a firm line. Now, Jaewon is back, and he's older, sharper, and more relentless than ever. As time goes by, Yeodan can no longer ignore how much has changed. The boy who once trailed after him like a shadow now stands before him as a man, and Yeodan isn't quite sure how long he can keep denying the spark.