In 2010, Yesung starred in the title role of musical "Hong Gil Dong", alongside bandmate Sungmin who also played the historical figure Hong Gildong. It played at the Woori Financial Art Hall at the Olympic Park from February 18, to April 18, 2010. On March 31, 2010, Yesung contributed to the OST of television drama "Cinderella's Sister", starring Moon Geun-young and Chun Jung-myung. The song, "It Has To Be You", is a ballad that tells the story about a man who refused to look for another girl, except for the one he loved. On June 4, Yesung performed it for the first time, and his first solo stage, on "Music Bank" which reached #3 on show's K-Chart.