Subspace

"Asora" (亜空), is a special alternate space created by Tomoe using her powers of manipulating space and illusions.

Description
Originally a void alternate space, which was used by Shèn to trap its opponent. To access the space, Shèn used her mist as an intermediary gates. Its size is based on the amount of magic power. Inside Asora, Shèn had the ability to limit the usage of magic of the people trapped inside and can also bend the laws of physics. Also for some reason, Shèn's body is detached from it, so any damage in there won't affect its real body.

But after Tomoe's pact with Makoto, the alternate space changed not only in size, but it transformed into a whole different land complete with its own ecology and environment, which is similar to that of Earth, mainly because of Makoto's influence. And with each new pact that Makoto forms, the environment expands and new ecology is added. The size of the Asora also increases with increase in Makoto's powers (though ecology and environment isn't changed in this case).