UPDATE: hard-subbed video is now available
This is an excerpt from Beautiful Man (Bel Ami) summer festival -Beautiful Story- held on July 19th. In the event, there were some missions to clear. This is one of them. Jang Keun Suk and Lee Jang Woo had to write a love letter to IU to get her heart. The winner needed to move her heart. JKS wrote a love letter as if it had written by MaTe To BoTong. So touching and sweet!
English translation: tenshi_akuma