Chaos

Ilias: "This, this Is the layer of nothingness...!? The nothingness is materializing and devouring the spaces...! If this spreads further, the whole world will become nothingness... Is that... the 'chaos covering the world' means...? We have to go further. Don`t touch it. If you touch it, the outcome will be the disappearence..."

Sonya: "Oh? It`ll disappear if I touch it?"

Illias: "...of your hand..."

Sonya: "Gah! I`ve almost touched it-!"

-Ilias and Sonya, at the 3rd Tartarus

"It turns out that this world didn`t follow the correct history. Somewhere in this history, the paradox occured, and it turns every space and the world itself into chaos. Chaos is the nothingness. Both are the same thing. And the most significant paradox it seems, originated from this other universe. The paradox from this other universe... it made a chain reaction that affected this world. And the whole parallel universes will collide with each other. Then, the whole of all universes will be devoured by the chaos... and what will be left is complete 'nothingness'."

-La Croix, at the Administrator tower

Chaos, or Nothingness, is the inter-dimensional phenomenon occuring in Monster Girl Quest: Paradox. It had started from a unknown parallel universe where the first paradox occured, and now spreads through all other universes.

The apoptosis phenomenon is an immune mechanism phenomenon of twisted dimensions to make this slow by preventing inter-world interactions, which are fruitless endeavors since the chaos spreads too fast.