Kim Jae Hwan is back with a new album!

On December 27 KST, the Swing Entertainment solo artist released his fourth mini album 'The Letter,' the first of his releases that he self-produced. He also participated as a lyricist and composer for all five tracks on the album, including the title track "Unforgettable."

"Unforgettable" expresses the torment felt when one wants to forget everything about a past relationship but finds themselves unable to. The moving ballad contains the feelings of a man heartbroken by the appearance of a former lover who is not getting along as well as himself.

Check out the music video above!