When delinquent transfer Ban Taehyeon, rumored to be the bawler at the center of a schoolyard fight, walks into class, the strict and upright Kang Hyeonbeom makes it his mission to keep him in check. Determined to reform Taehyeon into a model student, Hyeonbeom starts watching his every move... only to find himself slowly drawn into Taehyeon's orbit. As the line between discipline and friendship starts to blur, could Hyeonbeom really be the one getting "reformed" instead?