Mu-Sik's group, Saengcream-Pa is on the search for "Ares' Heart.' Their only lead, Jae-Yeong Jung is no help. When Mu-Sik Gae, the great number two is suddenly forced into living with this selfish orphan, he thinks it'll only take a few days. But it doesn't and as time passes, whether it may be as planned or his own emotions, Mu-Sik cannot help but feel his heart flutter when he's near her... Where in the world is that diamond?