Super Junior's '83 line, Leeteuk and Heechul, have finally debuted as a unit.

Super Junior's same-age friends Leeteuk and Heechul released their first mini-album as the '83z unit.

The title track, "Promise for You," is based on a band sound with a 1990s and 2000s vibe, so the more you listen to it, the more refreshing it feels.

The music video, which tells a story of friendship set against the backdrop of a fictional Bus No. 83, also had a unique concept.