Lee Kwang Soo and Kim Jong Kook showed off their bromance on the set of 'Sound of Heart'!





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On December 30, Lee Kwang Soo's agency released behind-the-scene photos from an episode called 'Twins,' where Kim Jong Kook played twin cousins of Lee Kwang Soo's character. The singer portrayed two characters well, earning praise from the staff.�





The two friends look friendly yet serious while practicing their lines and taking selfies!









