- First Summer Uika (Founding member)
- Hirano Nozomi (Founding member)
- Momose Momo (Joined January 14th, 2015)
- Akira (Joined August 25th, 2016)
- Pour Lui (Joined June 6th, 2018)
- Yasui Yuuhi (Joined January 14th, 2015, withdrew August 25th, 2016)
Early History, 2014-2015
On April 6th, 2016, BILLIE IDLE®︎ released the EP "4 in 1" THE OFFICIAL BOOTLEG. Each track was a solo song for each of the members, with the exception of Hirano Nozomi whose song featured First Summer Uika and other former members of BiS on guest vocals.
In the summer 0f 2016, Yasui Yuuhi went on indefinite hiatus for an unspecified health problem. In September it was announced that Yasui had graduated and would be replaced by Momose Akira, the younger sister of Momo.
On April 26th 2017, BILLIE IDLE®︎ released two albums at once; a live album, LAUNCHING OUT, and BILLIed IDLE, a best-of album with songs updated with Akira's vocals. BILLIE IDLE®︎ released their first CD single MY WAY in August 2017.
In the Fall, members First Summer Uika and Momose Momo provided guest vocals on the N.E.R.D song "Secret Life Of Tigers".
On November 1st, they released the single Sayonara Romantic and their fourth album LAST ALBUM was released shortly after on the 22nd. While promoting the release of this album, their producer Watanabe Junnosuke claimed that there would be "major changes" to the group in 2018.
BILLIE IDLE®︎ released P.S.R.I.P. on March 21st, which was revealed to be their final single with Watanabe as a producer. On April 1st, BILLIE IDLE®︎ released an "April Fools" video teasing a new member, which was deleted the following day.
On May 12th, former BiS founder and leader Pour Lui made a surprise appearance during the encore of BILLIE IDLE®︎'s P.S.R.I.P Tour finale where it was announced that she had joined BILLIE IDLE®︎. Pour Lui's first show was their June 6th one-man at Akasaka BLITZ.
On July 4th, BILLIE IDLE®︎'s second best-of album, BILLIed IDLE 2.0 would be released July 4th. Like the previous BILLIed IDLE album, all the songs were re-recorded to include Pour Lui's vocals. This was followed by their first original album with Pour Lui (and what would be their final album), NOT IDOL, on November 7th. A song from the album, Bye Bye Loneliness, was later released as a single on December 19th.
On October 16th, 2019, BILLIE IDLE®︎ announced that they would disband at the end of December. One of the main reasons given by producer NIGO was that the group was not profitable enough. BILLIE IDLE®︎ disbanded at the finale of their LAST ORGY tour on December 28th, 2019.
- Although they are not an official WACK unit, they were listed on WACK's official website, and was produced by Watanabe until early 2018.
- As of 2018, a majority of the group consists of former BiS members.
- When asked about their "NOT IDOL" theming, their explanation was that although they perform like idols, they do un-idol like things.