An audition was held for girls between 15 and 29 to record their own versions of the song and post it to Greeeen's official Line account.
They selected 15-year-old Meri and Kana, 16-year-old Hima and 17-year-old Noa, due to their "pure and transparent" sound rather than their vocal abilities.
[4] The members' identities remain hidden, and they did not attend public events;[5][6] they are displayed as cartoon-drawn images of themselves.
[7] "Ai Uta ~since 2007~" was released in both CD and digital formats in March 2015, and it reached number 1 on various weekly charts, including iTunes, RecoChoku and 8 other platforms.
[5] They released their second single, "Pocket" (ポケット), written by Greeeen, as the theme song to Nippon Animation's 40th anniversary film Sinbad: Sora Tobu Hime to Himitsu no Shima.