Phantasma (影の国, fantazuma) is another world created by the Aureole. Phantasma is affiliated with a higher dimension. To keep up with the wishes of the Liber Ark citizens, the Aureole created Phantasma as a subsystem to process all these requests. It became a self-governing world to realise multiple possible worlds.
To fulfil the wishes of Liber Ark citizens and therefore to justify its existence, the Sept-Terrion of Space, the Aureole, created Phantasma as a fictional world. It is a reflection of the material world, albeit with a number of changes and with its own rules.
It came into existence as a subsystem of the Aureole to process the vast amount of wishes. This duality of the Aureole was something faction ruler Celeste von Auslese kept in mind during drafting the Sealing Mechanism. In order to have the plan succeed, they developed the Recluse Cube mechanism, a unique terminal which could directly interfere with Phantasma without having to rely on the Aureole. Using this artifact, Celeste implemented a fragment of herself into the Recluse Cube.