On May 11th, Girl's Day agency Dream Tea Entertainment released the jacket image of their project single, Hello Bubble.

The image showed off unique styles of each member. Hyeri styled an unbalanced modern bob style in vanilla gold color. Minah showed layered hairstyle in pink rose champagne color to appeal her femininity. Yura showed off soft chocolate brown hair color to appeal her natural looks and Sojin styled a dark hair color that reminds viewers of sweet dark chocolate.

"We're collaborating with mise en scène hair care product company for this project to create a theme that will allow each member to show off her individuality. The new project single will feature unique music, fashion, and choreography as well," Dream Tea Entertainment explained.

Track and music video of "Hello Bubble" will be released at 12 PM KST on May 12th.