This is the untold story of the Sword Princess and the Song Princess! Yuki Setsuna's beloved popular light novel, "Crimson Blade Princess: Flame Sword Princess." The members of the Nijigasaki Academy School Idol Club have decided to create a mini film based on it. As they begin filming a movie starring the Red Princess, played by Setsuna, the group carries a special feeling that Setsuna holds because she loves it so much──. "Let's do our best to convey Setsuna-chan's feelings of 'love' together!" Fragments of their youth are now here as a novel version. A newfound thrill has been discovered──.