Seol A, EXY, and Soobin will make up the "Sweet Unit" sub-group.
Choa is the first member of the girl group AOA to have a solo debut.
The 12-member group will be the largest girl group in K-pop history.
As news of a solo album from the Girls' Generation member spread, SM Entertainment stepped in and put an end to the speculation - sort of.
Currently appearing on 'Unpretty Rapstar 2,' the girl group member is also preparing for a solo debut.
The new song will be a medium-tempo ballad, similiar to the singer's solo debut song.
The "storm" in the title refers to the only thing that can save a person in the midst of a ferocious storm: love.
The new boy band will release the full track on November 10.