At a typical elementary school in Japan, yearly chores are being distributed. Yuri and 3 other students are chosen to be the beneficiaries of the alien hats for the year. Alien hats?! Yuri's sentiments, exactly. Despite her misgivings, she and her classmates must round up stray aliens that have escaped from a crashed spaceship -- with the help of the alien hats, of course.
On the battlefields of World War II, a new threat is realized as a mysterious ship from the future is warped back in time to the 1940s. The ships' two living passengers are the only ones who know its whereabouts. Now two elite agents must stop the Nazis from capturing the survivors, finding the ship, and launching their diabolical plan to take over the world, codename: URDA.