This story takes place after the Girls Und Panzer der Film where boys are suddenly allowed to participate in Senshado. It's about a boy that suddenly decides to take up Senshado and leave behind his normal life and start a new one. He meets Miho and the rest of the characters in his adventure.

The Atlantic Ocean, 20xx. The war between the alien Sirens and humanity has been raging for decades, with the Sirens having a seemingly unbreakable death grip of Earth's oceans. With their advanced technology, the Sirens seemingly have the upper hand on all fronts. Among this advanced arsenal of technology, were small blue devices called wisdom cubes, Wisdom cubes each contained the power to make even the most delusional fantasies become a reality. But despite the sirens understanding of the universe, there is still some things they do not know.... ----- Operation Rheinübung, May 1941 The Atlantic Ocean. Two giant German warships prowl The Atlantic, seeking to change the course of a war on a scale of which the world has never seen. The first one, the Prinz Eugen, a massive heavy cruiser. And trailing behind her... The deadliest warship to ever set sail in the world. The Battleship Bismarck. The pride of a nation.... Built to lead a Warmachine, rule the waves, and lead the Kriegsmarine into battle.. The 50,000 ton beast made of steel makes all shiver before his menacing guns. Normally, this giant warship would be used to demolish British convoys, starving them of supplies, not repel an alien invasion. But fate, and history as we know it, has different plans.......