Behind-the-scenes of Shōjo☆Kageki Revue Starlight 3rd StarLive "Starry Diamond" concert.

The play tells a new original story that features characters from the Shōjo☆Kageki Revue Starlight Re LIVE mobile game, featuring and primarily focused on the Edels and Junior High students of Siegfeld Institute of Music. It also features all three Seiran General Art Institute students, as well as Claudine Saijo from Seisho Music Academy, Fumi Yumeoji from Rinmeikan Girls School, and Shizuha Kocho from Frontier School of Arts.

Siegfeld Institute of Music Junior High. An educational institution established for the purpose of training Rohedelstein, the future candidates for the roles of Edels. Two transfer students from Germany are due to enrol in the Junior High. One is Stella Takachiho, whose heritage is descended from Siegfeld's own prestigious family. The other is Shiro Ogami, Stella's exclusive maid. With the pair's transfer comes a drastic change in the fates of fellow Junior High students Ryoko Kobato, Minku Umibe, and Kuina Moriyasu. Liu Mei Fan works hard to meet the expectations of Akira Yukishiro and Michiru Otori, who are searching for a stage girl to carry Siegfeld on their backs. The ones who must entrust it, and the ones who must be entrusted with it—the symbol of the noble king, "Regalia", will end up...

The story involves a boy and his younger sister whose dog Papadoll is missing. They find out that he has been abducted by anthropomorphic cats to be brought to a world called Banapal Witt, which is built on top of a giant sleeping cat. There the sun turns poor Papadoll into a bizarre giant monster. He becomes the weapon and beloved pet of a spoiled Princess who turns everything she touches into balloons. She plans to use Papadoll and a giant inflatable mouse to control the sleeping cat and thus Banapal Witt itself.

An asteroid collision brought with it a deadly menace known as "Shinobi." Faced with destruction, humanity retreated to land reclaimed from the sea. The one ray of hope is a device that can fight the Shinbo called "The Mechanical Divine General." Ame, the princess of the refugees, and Suō, who carries the blood of the Yagyū family, must awaken its power in order to save the world.

After some pushing by Irene and her father and a lack of support otherwise, Kokoro stubbornly quits her job as a police detective to become an idol. She soon finds the idol life draining and starts to miss her old detective life. When Henriette notices Sherlock's loneliness without her, she stages a statue theft in order to convince Kokoro to return to the force.