“Are you prepared to fully devote yourselves to Roselia?” To reach the stage of “FES.“, Yukina Minato decides to form a band. Each holding their own convictions, the members of the band come together. The five girls now begin their journey to the top as Roselia... This is the story of their “promise” made to each other, from the start of the band to their challenge towards FUTURE WORLD FES!「你们有为Roselia赌上一切的觉悟吗？」为了登上音乐祭，凑友希那下定决心要组成乐团。各自怀抱着不同意念的成员们就这样聚到了她的身边。五人以Roselia的身分，以顶点为目标前进――这是一部描写从她们组团开始，直到挑战FUTURE WORLD FES之间的『约定』的故事。