After crashing her ex-boyfriend's wedding, high school teacher Siyeon is drinking alone at a hotel bar when a handsome, familiar-looking man approaches. Desperate for comfort, she decides to have a passionate one-night stand with him. However, her world is turned upside down when he shows up at her high school and is revealed to be her new coworker. He's actually Hajun Cha, a student she taught just a few years ago. Siyeon wants to forget their night together, but Hajun isn't having it. "Can we do it one more time, teacher?"