On October 10 at midnight KST, Billlie announced their comeback plan through a teaser scheduler for the first single album ‘side-B : memoirs of echo unseen.'

According to the teaser schedule titled 'Billlendar,' Billlie is prepping for their first single album release with a new set of teaser content that will be released beginning October 11 at midnight KST. The girl group has much in store for fans until the album's release on October 23 at 6 PM KST.

So check out the teaser chart below and mark your calendars!