Yejun has worked tirelessly to put his troubled past behind him and is now a respected history teacher. However, when his estranged high school friend, Minhyuk, unexpectedly shows up as his teaching assistant, Yejun’s carefully constructed new life is threatened. Minhyuk is a painful reminder of Yejun’s past ever since their relationship ended on a bitter note. Despite any attempts to keep their interaction strictly professional, Minhyuk persists in acting as if they are still close friends. Yejun knows that moving on from past wounds isn’t as easy as retaking a test, but could they redefine their relationship from colleagues to lovers?