BTS' new song "Film out" will be used as the theme song for the movie 'Gekijoban Signal: Choki Mikaiketsu Jiken Sosahan' that's due out on April 2. 

The story of the upcoming movie is a continuation of the drama series 'Signal: Choki Mikaiketsu Jiken Sosahan' that aired back in 2018. Sakaguchi Kentaro will reprise his role of detective Saegusa Kento. 

BTS sang the theme song "Don't Leave Me" for the drama series and was asked to be in charge of the theme song again. For the new song "Film out," they collaborated with back number. It's described as a ballad that's full of emotion about "a person that will not disappear from one's heart." 

Producer JUNG KOOK, who was inspired by a melody line developed by Shimizu Iyori (back number), suggested a new melody, which eventually led to the creation of "Film out." This is back number's first time providing a song to another artist. 

You can listen to a clip of "Film out" in the trailer below.