NakJoon's JYP Entertainment labelmate and good friend Young K of DAY6 played a major role in his comeback album.

SEE ALSO: Woman attempts to jump from 19th floor building in Gangnam, rescued by police mere seconds before her jump

As revealed via a 'live lyrics' teaser video released on October 6, the idol was actually the songwriter behind the B-side track on the solo artist's upcoming album, a painful and emotional ballad entitled "Sleep Mode." The song deals with the feelings of just wanting to be alone after a hard break-up, but at the same time, feeling as if you are still waiting for your ex to return.

Joining Young K on the production side of things is composer Eco Bridge, who has formally worked on a number of hits for popular Korean ballad artists, including Jungyup, Naul, Kim Bum Soo, and Choi Baek Ho.

Fans can check out the full track when NakJoon's album drops on October 10.

Check out the full live lyrics video for "Sleep Mode" above!