A mage platoon supplies air support during battle. The leader of the platoon is a little girl--Second Lieutenant Tanya Degurechaff. One of her soldiers realizes something about the Second Lieutenant seems terrifying.
More of Tanya's background as a new soldier for the Empire is revealed. She must test dangerous magic jewels amidst interference by the godlike being. Her desperate effort to avoid dangers of a test pilot mage lands her on the front lines.
The main forces has arrived to the Rheine theater. Tanya is ordered to leave the front and join the university. During her studies she meet Hans von Zettour and propose him the the first world war and to create a mage battalion.
The Empire is launching a seemingly foolish attack on the Entente Alliance in the middle of winter. They lack the supplies to successfully invade, but Tanya realizes that this attack is intended to distract from the real mission.
The war with the Entente Alliance is done, and it's back to the Rhine for Tanya and her forces. The Republic troops are highly trained and stronger than any she's faced before.
The last enemy on the continent is the Republic, and the Empire has come up with a bold plan to take them out. Of course, Tanya is sent to the forefront of this operation, and is forced to take on the entire Republic army by herself!
Tanya's mission is a success, and the Republic is surrounded and crippled. But on her way back, she runs into a group of allied mages lead by Anton Souix, whose one mission in life is to take down the Devil of the Rhine!
As Tanya's battalion carries out their final mission, they are attacked by defensive forces. They launch a counterattack, and come out victorious. This seemingly ends the war - but Tanya soon realizes the celebration may be premature.
The victory celebration for the 203rd mage battalion has been cut short. Republican forces are still active on the Southern Continent. Generals Zettour and Rudersdorf decide to send Tanya and her battalion to eliminate the enemy once and for all.
