Unaired episode included with the 7th volume of the BD/DVD release of Kobayashi-san Chi no Maid Dragon.

In the far future, humans abandon a devastated Earth and traveled to outer space. However, due to unknown phenomenon that prevents them from traveling into space, humanity returns to Earth only to find it inhospitable except for Japan. To accommodate the entire human population, pocket dimensions are created around Japan to house in the populace. In order to find a way to return to outer space, the humans began reenacting human history according to the Holy book Testament. But in the year 1413 of the Testament Era, the nations of the pocket dimensions invade and conquer Japan, dividing the territory into feudal fiefdoms and forcing the original inhabitants of Japan to leave. It is now the year 1648 of the Testament Era, the refugees of Japan now live in the city ship Musashi, where it constantly travels around Japan while being watched by the Testament Union, the authority that runs the re-enactment of history. However, rumors of an apocalypse and war begin to spread when the Testament stops revealing what happens next after 1648. Taking advantage of this situation, Toori Aoi, head of Musashi Ariadust Academy's Supreme Federation and President of the student council, leads his fellow classmates to use this opportunity to regain their homeland. (Source: Wikipedia)

After the events of Mask of Deception, the Yamato Empire is now ruled with an iron fist by a ruthless usurper who seeks to subjugate all before him. It's up to a couple of familiar faces to band together against the might of the Imperial army, and the fate of the world hangs in the balance as nations and generals must pick a side to fight with in this perilous civil war. Secrets will be revealed, friendships will be tested, and battles will be fought. Will peace and order be restored or will victory at any cost be the beginning of the end?

After Akihito Kanbara reunites with Mirai Kuriyama—whom he believed had vanished after defeating Beyond the Boundary—he discovers a heartbreaking fact: Mirai has lost all memory of him, their friends, and her past as a Spirit Warrior. Akihito is utterly devastated, but realizes that she has a unique opportunity. Mirai can finally live the life of a normal girl—where she'll be completely devoid of the supernatural society that both shunned and used her. While it's all for the sake of Mirai's happiness, the price is costly—Akihito and his friends must keep her true origins a secret from her, and as a result avoid befriending her. However, the troubling memories of Mirai's old life gradually begin to resurface, and a mysterious new evil leads a group of shadow-like creatures into the city with the goal of seeking her out. As the situations become dire, Akihito must fight to protect himself, his closest friends, and Mirai—the bespectacled beauty he holds most dear. [Written by MAL Rewrite]