It is the 1920s, and Japan is under attack by demonic invaders. The government has designed sturdy, albeit steam-powered, robot armor suits for the impending battle, but only young ladies with the proper combination of virtue and spirit can pilot the robots successfully.

Enter young Sakura, arriving in the Imperial Capital from the countryside to join the Imperial Flower Combat Troop. She has the qualifications to be a fine robot pilot, but she's surprised to learn that this secret Defense Force has a cover story as a musical theatre troupe-and they take their cover jobs very seriously indeed. It's costumes, line readings and robot combat galore, as Sakura struggles to learn the ropes, learn her lines, and do her part to save the nation!