He Was Cool by Lee Hwan-kyung

6.60

When high school girl Han Ye-won finds an offensive note on the internet school board left by arrogant Ji Eun-seong from vocational school, she replies even more offensively. She doesn't know he's hot-tempered and well-known as a bully. So when Ji Eun-seong starts looking for her to teach her a lesson, Han Ye-won realizes how big her mistake was.