Die-hard K-drama fans know the undeniable impact of supporting characters and second leads. While they may not be the central focus, many of them exude serious main character energy. These roles aren’t just well-written—they’re brought to life with such brilliance by the actors that they become unforgettable, often stealing the spotlight from the leads. Their performances elevate these characters to iconic status, etching them into the hearts and minds of fans forever.

Here's why you should watch Seo Kang Joon go back to high school in the new action/thriller "Undercover High School"!