Actor Opens Up About Challenging Stunts and Getting Back into Acting After Military Service South Korean actor Seo Kang-joon has described a specific day while filming his new drama Undercover High School as one of the hardest he has ever faced. The 31-year-old, who plays Jung Hae-sung, an undercover National Intelligence Service agent posing as a high school student, opened up about the grueling experience during a recent interview. In episode four, Kang-joon filmed an intense action sequence set in a warehouse, where his character battles five to seven adversaries. Despite his preparations, the heat and the physical demands of the scene made it one of the toughest moments of his career. "It was extremely tough, especially in the scorching heat. If I had to choose the hardest days of my life, filming that scene would be among the top three," Kang-joon said. The demanding stunt required him to fight multiple opponents while wearing a school uniform, making it physically exhausting. "The entire sequence was a major challenge, but it was the toughest in terms of physicality," he added. Co-star Jin Ki-joo, who plays Hae-sung’s homeroom teacher, Oh Su-a, also shared her experience. She had to perform action scenes while wearing a dress and spent hours learning how to play the piano for one particular scene where her character plays the school anthem. "I practised for seven hours straight on the first day," she said, noting how immersed she became in her preparation. Undercover High School marks Kang-joon’s return to …
