The Mnemeion (a.k.a. the "Graveyard" or "Cemetery") is an ancient mobile fortress starship made by the Innovation Empire to defend themselves from Beasts. The Zail Family ordered its creation from a deactivated Blue Flower during the Great War. There are no known records of Mnemeion's actual field performance but this is most likely due to the ravages of the war then.
Mnemeion has a huge role in Another Episode-2 A Village Where You Are.
The Mnemeion was discovered already inactive and lacking its core in the 7th Ground Zero on Vine. It was then declared as a lost technology. Research on the site confirmed that the Vine Ground Zero was a derelict shipyard of the Innovation Empire.
In CC 400, during the First Battle of Tobal, the Knight Order prioritized the recovery of the uninhabited Vine over the inhabited planet Tobal due to the perceived breakthrough importance of Mnemeion in the Human-Beast conflict. Unfortunately, neither the Knight Order nor AE had the proper technological capacity to reactivate Mnemeion.
It was further studied but ultimately left in its preserved state until the arrival of Lieutenant General Tinie in CC 431 who attempted to reactivate it with the core of a Blue Flower that fell on Tobal. Tinie used another Innovation Empire lost technology, the "God's Pillars", to act as a controller to the core and Mnemeion. The plan was successful but EX-Type Two Chatterbox killed and replaced Tinie as Mnemeion's commander. Mnemeion was then used extensively by the Beasts in the Third Battle of Tobal to resume Queen E-34's war to exterminate humanity.
Former Top Sword Sion Zail took over command of Mnemeion upon the death of Chatterbox by using her Zail code. Still, she cannot fully control the fortress to stop destroying Tobal as per the last instructions of Chatterbox. Further asserting her code, Sion then instructs Mnemeion to warp at the rear of the Alternative League fleet that has intervened in the Tobal Civil War specifically so that Supreme Commander Dry Leonhard would be forced to battle Mnemeion. Dry does so and was able to burn huge swaths of the fortress. With little energy left, Sion was finally able to calm down Mnemeion. Sion then instructs the fortress to warp into an isolated but serene unknown planet in the distant unexplored regions of the universe.
Many decades later, the unknown planet is discovered by an elderly Mio, now known as a leading expert in planetary research and terraforming. She found the wreckage of the inactive Mnemeion half-submerged in an ocean. It can be surmised that Sion was able to fully deactivate the core as there were no traces of erosion on the tranquil planet. There were evidences of a person living in the planet but Professor Mio corrects her understudy as she believes there were two people. Mio then names her discovery as Planet "Sion".
The Mnemeion possess fearsome weaponry such as numerous large and small particle beam cannons, concentrated on its underbelly and the tail which can unleash a devastating bombardment on a given surface target.
During the Third Battle of Tobal, Chatterbox hacked into the Golden Ring Orbital Cannon and merged it with the Mnemeion.
The Mnemeion appears to be able to operate both within atmospheric conditions and outer space. While the ancient mobile fortress has a slow cruising speed due to its massive size, it can use instantaneous independent warp similar to Black Hole Engines to travel to its destination.
As a fortress, it is presumed to have facilities to maintain a garrison.
- Ancient Mobile Fortress Avalon