After wrapping up promotions with her former group Iz*One on April 29, 2021, Kwon Eun-bi stated through an interview with Esquire magazine in July that she was planning on releasing an album sometime within the year.

On August 5, 2021, South Korean media outlet Star News reported that Kwon Eun-bi would be the first member from Iz*One to make her solo debut and was filming the music video and doing photoshoots for her upcoming album which would be released at the end of August.

Woollim Entertainment then confirmed on the same day that she was "working on making the final touches on her solo album".

On August 11, another teaser image was uploaded on the artist's official SNS accounts, revealing the title of the EP, Open.

[7] The lead single "Door" is described as an electro swing song that uses brass instruments and has elements of jazz.

The song was composed by Hwang Hyun (Monotree) and Jung Ho-hyun (e.one) whom Eunbi had previously worked with several times when she was a member of Iz*One.

"Amigo" is a moombahton and trap song written and composed by Inner Child (MonoTree) which features her labelmate Babysoul of Lovelyz.

The final track "Eternity" is an acoustic pop song that is dedicated to her fans and is composed by Park Tae-jin with lyrics written by Kim Hyun-ah.

Woollim Entertainment also announced that Eunbi would be holding online video fansigns and an album showcase through her V Live channel on August 24.