Best Mistake 1: The Movie.

Kim Yeon Do (Lee Eun Jae) is a studious high school girl whose life is being made miserable by a boy from her past. Despite all of her efforts, she can't get peace as he won't leave her alone. So she hatches a plan. On her social media pages, she posts a picture of another boy, in the hope that this move will put an end to the irritation. But this move turns out to have unexpected consequences: It turns out that the boy in the picture is actually one of her schoolmates. Named Ji Hyun Ho (Kang Yul), he is a bit of a loose cannon. Although he is very popular, he dislikes studying - and prefers play. The rest of the school soon learns about the social media post, as news spreads fast in the classroom! This leads to a number of run-ins with ji Hyun Ho. But the more they get to know one another, the closer they get - causing yet further complications for a whole host of classmates!