Shimazu Toyohisa is the real-life samurai who fought in the pivotal Battle of Sekigahara. In his dying moments, Shimazu is transported to a world of magic with other famous warriors throughout history. These warriors are forced to fight each other in an endless battle.
In 1939, the imperialist nation of Germania launched a sudden invasion of its neighboring countries. This conflagration engulfed all of Europe in one fell swoop, and the era was dragged into the maelstrom of war. Then in 1940, Germania set its sights on Elystadt, a tiny principality blessed with breathtaking greenery and water in the Alps. Izetta is a descendant of a clan of witches who had passed down mysterious powers for generations. Since she was little, she and her grandmother lived their lives on the road, traveling between European countries in order to hide these powers. Fiine is the sole daughter in line to succeed Rudolph III, the ruler of the Principality of Elystadt. Since her father has been stricken by illness, she has been busy preparing for Germania's invasion in his stead.