Young Sakura arrives in Capital City to fight for the Imperial Floral Capital Defense Force, but all she finds is a weird opera company preparing for a big performance. What's worse, the ladies in the company won't let Sakura join in any of their Rheingold games. Can she win them over by unleashing her Spirit Energy?

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.