Senjou no Waltz tells the story of village girl Ran, who obtained massive power from a cursed magic sword after losing her parents and hometown. She ended up at an ultranationalistic military school known as Nirvana. It was a unique school, a country in its own right gathering boys and girls that excelled in combat.

One day, a girl suddenly had everything stolen from her. Her hometown, her parents... and in exchange she obtained "power". She took hold of a sword holding massive power in order to protect herself and those she cares about, the 'cursed magic sword'. The girl, who now possessed a power that could shake the nation, had no choice but to live on the battlefield. She ended up at an ultranationalistic military school known as 'Nirvana'. It was a unique school, a country in its own right gathering boys and girls that excelled in combat. It is here the girl meets many different people and begins to forge deep bonds. And also, begins discovering where she belongs, a place in the world that she was sure she had lost. This is that girl's story, of her and the 'talking magic sword'.