This world is called rotten earth.
There is no aura, no way of heaven, no supernatural source of energy. There is only "decay" - a ubiquitous force that slowly erodes all things.
Decay is not rust. Rust only eats iron, rot eats everything.
Stones will decay, wood will decay, water will decay into stagnant water, fire will decay into cold ashes, the human body will decay, memories will decay, emotions will decay, and even time itself will decay - the flow of time in some areas of the rotten soil is slower than that in the outside world, just because time "rots" there.
No one knows where decay comes from. There is only one sentence engraved on the oldest stone tablet in Ruitu:
"All things decay, but rust lasts forever."
The meaning of this sentence is: all living things will eventually be eroded by decay, but "rust" - the product of decay, the residue of decay, the corpse of decay - can exist forever. Iron decays and turns into rust, but rust will not continue to decay. Rust is the end.
Therefore, the practitioners in this world are not cultivating spiritual energy or the way of heaven, but cultivating rust.
They extract rust from decayed objects, incorporate it into themselves, and use rust as their strength. These people are called "Rust Eaters".
