According to bandwagon, BTS first met Back Number in 2017, but the two groups have collaborated for the first time on a new song called "Film Out", which will be the theme song for Signal, a Japanese film adapted from a series of the same name.
#BTS 新曲「Film out」が『劇場版シグナル 長期未解決事件捜査班』主題歌に決定！back numberと最高のコラボレーションが実現！@backnumberstaff @signal_ktv
— BTS JAPAN OFFICIAL (@BTS_jp_official) February 16, 2021
詳細はこちら→ https://t.co/WlwOiQtXDB
BTS' "Don't Leave Me" song was featured in the Signal series soundtrack in 2018.
Jungkook of BTS is said to have helped create "Film Out" alongside Back Number vocalist Iyori Shimizu.
bandwagon reports that "Film Out" is an emotional ballad about "a person who still comes to mind and never disappears from the heart."
A snippet of "Film Out" is previewed during the trailer for Signal.
