Former contestants on Mnet's Superstar K2, Jang Jae In and Kang Seung Yoon were reported to be doing a collaboration performance on today's M! Countdown. While performing Lee Moon Sae's "By Living in This World", the contrast in their musical styles and vocals joined to bring the classic track to life on stage. Though it was sad to see these two wonderful performers go on Superstar K2, it's great to see them reunited for programs such as these! Enjoy the duet below!