Synopsis
In a distant future, humanity abandons the ruined Earth and migrates into space, but an unknown force stops space travel, forcing a return to Earth, which is now only livable in Japan. To sustain the entire population, pocket dimensions are created around Japan. Humanity seeks to regain access to space by replaying human history according to the sacred text called the Testament. By Testament Era 1413, nations from these pocket dimensions invade and conquer Japan, splitting the land into feudal territories and displacing the original inhabitants. By Testament Era 1648, the displaced Japanese live on the city ship Musashi, which endlessly circles Japan under the watch of the Testament Union, the authority that manages the historical reenactments. As rumors of impending destruction and war spread because the Testament stops revealing events after 1648, Toori Aoi—the leader of Musashi Ariadust Academy's Supreme Federation and the student council president—along with her classmates, take this opportunity to reclaim their homeland.
