[3] Discussing "Always", Choi Min Hwan compared the song to "Satisfaction" in that one may feel a similar "atmosphere and a strength", but noted that there was more emphasis of sorrow in "Always".

[3] "Paper Plane" is a medium-tempo song, which features a dense snare drum.

[4] "Distance" was written by Kenn Kato, Song Seung Hyun and Lee Jae Jin, and composed by Corin.

[5] Lead singer Lee Hongki had difficulty singing the song, stating that the key he sang in was very high.

Island was in the midst of promoting in South Korea, which limited their time on the project.

Determined to convey the proper emotions of the songs, they "made sure to stop and interpret every part of the lyrics".

Island aimed to make 20 [Twenty] their most mature album to date.

Island held two release events for the album at Zepp Tokyo and the Hotarumachi Dōjima River Forum in Osaka, respectively.

An estimate of 10,000 winners of a lottery were in attendance in both events, where the band performed five songs.

[14] The following day, they performed acoustic versions of the songs "Stay", "Flower Rock", "Soyogi", and "Venus" on Space Shower TV.

[18] On the Billboard Japan Top Albums, 20 [Twenty] also debuted at number four.