Hakgyoro Gan Boss

Joo Si-Hyeon, a successful 33-year-old CEO, has decided to return to high school to get his diploma. As Si-Hyeon tries to find a way to balance school and work, Eun Ha-Im is worried about her new job as the older student's homeroom teacher. Ha-Im soon realizes that's the least of her worries, as it turns out Si-Hyeon is the same man she had a one-night stand with in Canada just months ago! The two thought they would never see each other again, but who knew they would meet in a classroom like this?

(Source: Tapas)