The unit consisted of 4 members, Yves, Go Won, Chuu and HyeJu (formerly Olivia Hye).

Currently the unit consists in 3 members, without Chuu, who was removed from Loona and consequently the lineup in November 2022.

On December 14, at midnight KST, a teaser photo of the latter was revealed with a caption "A mysterious girl is coming".

It was titled "Cinema Theory: Up & Line"[7] Their final member, HyeJu, was officially revealed with a teaser photo on March 17, at midnight KST.

[11][12] On May 19, a teaser photo was released revealing the title track "love4eva" and that it would be featuring Grimes, as some of her fans asked her to produce the group, as well.