He sang ballad track "Love Really Hurts" for the original soundtrack of television drama "Tazza", which aired from September 16, to November 25, 2008. In 2009, Yesung made his musical theatre debut in "Namhansanseong" (lit. South Korean Mountain Fortress), which is based on the novel of the same name by Kim Hoon, which is based on the historical incident of Byeongja Horan, at the Namhansanseong in Gyeonggi-do. But the musical focuses on the lives of common people and their spirit of survival during harsh situations. Yesung played villain "Jung Myung-soo", a servant-turned-interpreter who feels sad from being betrayed by his country, from October 9 to November 4, at the Seongnam Arts Center Opera House. On November 6, he made a surprise appearance on KBS' "Music Bank" with label mates SHINee in place of Jonghyun, who was recovering from influenza, in a performance of "Ring Ding Dong".