iirc the ending song is already out on Spotify but nothing from avex yet... The only thing I have seen about the band project is this insta account but then it could even be a fake one
https://www.instagram.com/blank_paper_jp/
One of the posts has a video as the second pic but nothing interesting just a logo and a bit of the song we already know
Since BACK-ON just released an album, and Kuu will probably do the same in the beginning of 2022, I guess they will announce the band after that. My guess is they made this song as a small test, to see if people would find out about them or even how they would react to the song without knowing who is behind it. It's weird af tbh lol
Avex has really lost their hand at marketing at this point imo, they drop things here and there digitally and hope it becomes a hit. It's also like what they're doing with Kalen Anzai (no shading her at all), she had one type of sound and imagery at her debut and then she just switched to another one and keeps on releasing random digital singles. She should have had an EP at least when the dorama about ayu debuted, and a full album by now... But seems like they want to keep trying on a lottery until a big hit comes up by pure luck. I hope blank paper doesnt have the same faith...