Anti-Space (also known as prime reality) is our reality as depicted in the Mysterious X Project universe and all connected universes. Reality is the state of things as they actually exist, rather than as they may appear or might be imagined in the baby waffle universes.

When characters exist their realities and enter Anti-Space, they are turned into toys or trophies and cannot move. Characters do not need to enter Anti-Space all the way; they can still process thinking and consciousness. A being called Irregular exists in this realm as objects not meant to be normally seen; it is depicted as wild, uncontrollable energy.

Interactions between Anti-Space and Postive-Space cannot be normally seen unless more universes cross over. At some point, the number of universes crossing triggers visibility of tampering. Characters being tampered in Anti-Space have no will of their own although they appear to do.

It is one of the few universes that cannot be returned from if entered; tampering with a character in Anti-Space must return to the universe they were originally from.