Billlie is making an exhilarating comeback with a brand-new mini-album.

On October 4 at midnight KST, the girls released a new set of teaser photos gearing up for the release of their 5th mini-album 'Appendix: Of All We Have Lost.' The girls exude their charisma and charm while captivating their fans with a more mature look.

Meanwhile, Billlie will pre-release "Trampoline" on October 11 at 1 PM KST and release the 5th mini-album on October 16 at 6 PM KST.

SEE ALSO: Billlie drop a release schedule for long-awaited 5th mini album 'appendix: Of All We Have Lost'