Plot
In 1926 Tokyo, steam power has become the city's primary energy source. At the Grand Imperial Theater in Ginza, the Imperial Combat Revue's Flower Division–a group of women consisting of swordswoman Sakura Shinguji, lead actress Sumire Kanzaki, Russian ex-soldier Maria Tachibana, French telekinetic Iris Chateaubriand, Ryukyu karate expert Kanna Kirishima, Chinese inventor Kohran Ri, Japanese-Italian aristocrat Orihime Soletta, and German dancer Leni Milchstraße–defends Tokyo against demonic attacks born from negative human elements using the Koubu-Kais, a group of steam-powered mechs, while also maintaining a cover as a theater troupe called the Imperial Revue. Meanwhile, Douglas-Stewart, an American corporation led by Brent Furlong, is determined to make the Flower Division obsolete through the use of Japhkiels, a type of unmanned mecha that are actually demons in disguise.
During the Christmas season, Ratchet Altair, the former leader of Orihime and Leni's failed Europe-based Star Division, arrives from New York City and joins the Flower Division as a new recruit in her efforts to set up a similar division in New York City. Dispatched to fight a fresh demon attack on the city that night, the Flower Division watch some of the demons being taken by the Japhkiels.
After the Flower Division suffers multiple disastrous battles, including one where Orihime and Leni's Koubu-Kai units get destroyed and replaced by their Eisenkleid units, Furlong and Imperial Army officer Haruyoshi Tanuma use their influence to capture the Imperial Combat Revue's commander Ikki Yoneda, seize the theater, and place the Flower Division on indefinite standby as well as their assistant commander Kaede Fujieda and the Moon Division under house arrest. Meanwhile, Furlong's near-immortal henchman Patrick Hamilton tricks Orihime into becoming his accomplice. Investigating Douglas-Stewart, Maria learns about the Japhkiels' true forms and encounters Hamilton, who met Maria during her time as a mafia hitwoman in New York. Despite being seriously injured, Maria flees from Douglas-Stewart.
Meanwhile, Sakura and the rest of the Flower Division launch an assault on the theater to retake their Koubu-Kais, though Ratchet's more violent approach causes friction with Sakura. After they free Kaede and the Wind Division and retake the theater, the Flower Division battles the demons and eventually use the Imperial Capital Barricade Formation to disintegrate them. The Flower Division later battles Orihime and Leni stops Ratchet from killing her in the chaos, allowing the group to free Orihime from Hamilton's control, though Leni and Orihime's Eisenkleids are destroyed in the process. Meanwhile, Moon Division captain Yuichi Kayama liberates Yoneda and destroys the Japhkiel incubation facilities with help from the Imperial Japanese Navy. Kayama attempts to arrest Furlong, but he escapes on a Japhkiel. Merging with the surviving Japhkiels, Furlong overpowers the Flower Division and destroys Ratchet's Eisenkleid in the process. Before Furlong can kill Sakura, Ichiro Ogami arrives in his F2 Koubu from Paris and reunites with the Flower Division to kill Furlong and the Japhkiels. Yoneda arrests Tanuma, and Maria uses a bullet infused with spirit energy to kill Hamilton.
In the aftermath, the Flower Division and Ratchet perform a musical play based on Kyōka Izumi's The Sea God's Villa. Through the play, Ratchet admits her anxieties following the collapse of the Star Division to Sakura and receives support and forgiveness from the Flower Division. Despite the unscripted deviations, the play is a great success.