Story
Film by Amineworks — Summer 2022, 1 episodes, Finished.
The concept behind the project is a "battle royale" between three idol units, each one led by a Sengoku-era commander who has been reincarnated as a music producer. The winner of the battle royale will be determined by sales numbers and voting at each live performance. The group that wins will hold a grand live performance to adopt the name of "the greatest under the heavens."
Synopsis via AniList (English).