The natural will obviously can affect the Post-mortem World, which is why Mazao always encounters misfortune there.
However, to say that this is all the natural will's effort to save itself, placing all the burden on Mazao's shoulders, seems somewhat exaggerated. The natural will might also be making efforts in other areas, and Mazao might just be one part of it.
I couldn't help but think of the giant full moon hanging over the night sky of the Post-mortem World. The Naraku Gospel which the Evangelical Institute now worships also seems to be an unknown will from outside that has invaded the human face of the Post-mortem World. Could it be the same entity capable of radiating its power into the Post-mortem World as the natural will?
But it seems illogical; if it's the manifestation of the Earth's natural will, then it should manifest in the form of the Earth. Why does it appear as a full moon?