Question: Which South Korean television drama series stars a boy group formed by S.M. Entertainment in 2008?
Sentence (from "TVXQ videography"): In July 2009, three of the members – later known as JYJ – left the group's Korean agency S.M. Entertainment, and TVXQ returned as a duo act with remaining members U-Know Yunho and Max Changmin in 2011.
Relevant evidence: No