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 acting after completing his military service in 2023. He explained how his time in the military helped him regain his stamina and maintain his connection to acting. “We ran 3km every morning during the military, which really boosted my fitness,” he said, adding that the physical activity during his breaks proved beneficial when he returned to the set.
As for how much his character aligns with his real-life personality, Kang-joon noted that both he and Hae-sung share a nuanced outlook on the world. “We both believe that light and dark co-exist. There’s beauty in flaws, and even in negativity, there’s something redeeming.”
The action-comedy series Undercover High School is streaming on Viu, with new episodes released every Saturday and Sunday.
