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'Running Man' members Gary, Song Ji Hyo, Kim Jong Kook, and even Lee Kwang Soo take their love over on to the set of 'Descendants of the Sun,' bringing tears and laughter with their heart-wrenching romance. 

Song Ji Hyo takes over Kim Ji Won and Gary Jin Goo, while Lee Kwang Soo and Kim Jong Kook play the much beloved 'Song-Song' couple. Lee Kwang Soo doesn't seem to be falling for Kim Jong Kook's childlike smile. Not to worry though, because slowly and surely Jong Kook is bound to win Kwang Soo's traitor heart over. I mean, come on. Who wouldn't fall for that smile??