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Changmin announced his participation in the 'Heirs' OST on Twitter, writing, "Right after attending Kun Myung hyung's wedding, I ran over here.. I definitely went there dressed nicely but I'm in pain mode at the studio ? Because it is a song that is not the style that I normally sing, it was difficult but the drama is jjang! ??? [Heirs] OST recording completed! It will be ON AIR Wednesday."

The song is apparently called "Moment" and it's composed by Kim Do Hoon. Changmin's sorrowful voice in the song sets the mood for the love story of Kim Tan (Lee Min Ho) and Cha Eun Sang (Park Shin Hye), so listen for it while you watch or maybe even re-watch the episode from the 17th!

It hasn't yet been revealed when the official release date for the song will be, but having been revealed on an episode already, it's expected to take place soon.