The newest photo shows Krystal�and EXO's Kai�in a couple photo, with Krystal leaning on Kai's shoulders. The vintage mood makes the photo even more melancholy.

SEE ALSO: f(x) to make a comeback with "Rum Pum Pum Pum" + new group and individual teaser photos

Their upcoming title track�is a pop dance track that compares belatedly finding one's first love to a wisdom tooth that grows last as it pushes aside the other teeth.

They'll actually be kicking off their comeback stages prior to the album release, starting off with their performance at 'M! Countdown' on the 25th. The 2nd full-length album 'Pink Tape' will be released on and offline on the 29th!

[Thanks to everyone who sent this in!]