SS501's Kim Hyung Joon and "Superstar K2" contestant Kim So Jung recently came together for a collaboration track, "Love Is", which will be included in the OST for the musical,�"Caffeine". "Love Is" is Kim Hyung Joon's first debut track in his transition from an idol star to a musical actor. Public interest about the duo has been rising, due to photos released of the two in the recording studio, on top of the fact that this is the first collaboration between an idol and a "Superstar K" contestant. Source + Photos: Newsen Tip: jackwon