On June 2 KST, LOONA unveiled a teaser poster revealing that all twelve members will be making a comeback for their 4th mini-album.

Earlier this year, LOONA's agency Blockberry Creative announced that member HaSeul will be sitting out from the girl group's next promotions.

In January this year, the agency revealed that HaSeul was diagnosed with intermittent anxiety symptoms and needed time to focus on her health. Since then, HaSeul has not participated in the group's activities except for the recording of a few songs from their album '#' and the lead single "365."

Finally, all twelve members are making a comeback as HaSeul's name appeared in the recent teaser poster. The poster also shows twelve eyes as they gaze directly into the camera.