[1] In midst of a break while on tour, Jung hung a "do not disturb" door hanger in front of his hotel room, inspiring the title of the record.

Jung described it as the "sweet" song on the record; the chorus was initially written in English, but was later translated to Korean.

[6] His first attempt at the genre, he described as a "party" song with elements of pop music which fixates around "repetitive" hooks and lyrics.

[2] "Not Anymore" is a R&B-pop ballad which serves homage to the sound and lyricism of the 1990s by following the melodic progression and the implementation of a synthesizer common during that time period.

[2][5] Jung co-wrote the song with a keyboardist, which whom he worked with on his first solo concert tour; Jeon Geun-hwa provides vocals for the chorus.

[5][6] Jung utilized a similar chord progression to "Last Leaf" from his debut studio album One Fine Day (2015), calling it an "extension" of the song.

The standard version cover of the mini-album depicts Jung in black-and-white monochrome, contrasted against colorful tropical plants in the form of decalcomania in order to emit a summery aura.

[8] Not part of the original design, the decalcomania was inspired by a trip Jung took to Hawaii, where he "fell in love with the place".

Shot in the Hongdae, Seoul, Jung collaborated with a photographer of Arena Korea magazine for the album photography.

[2][10] Designed and hand-drawn by Jung, the special version cover depicts a red door hanger affixed with a pupil, signifying that "the eye is watching".

[2][11] The album photography shows Jung donning white apparel as sun rays shimmer through curtains, producing a "relaxed" environment.

[3] On July 21, Jung began promoting "That Girl" by performing the song on weekly music chart shows.