Yoon Kyung-ah

A misunderstood loner is drawn out of his shell after transferring to another high school, where he comes across new ordeals and his first love. (imdb)

Kang Seok-Ho (Kim Soo-Ro) is an ordinary lawyer and former bike gang member. He then takes a position to revive a third rate high school named "Byeong-Mun High School". To revive the school, Kang Seok-Ho needs his students to become accepted into prestigious universities. (AsianWiki)