It looks like the guesses to their spoilers were completely correct. "Someday" is a song composed and written by member Hyunsik, who is BTOB's 'father of music'. It's going to be the boys' signature emotional ballad, with the rap line writing their own rap lyrics.
Cube Entertainment revealed, "It's a song that was too good to be just a song on the album, so we decided to release it as a pre-release."
The song will be dropping at midnight KST on February 24!