In the sacraf series, the spiritual belief is that the soul dies and the spirit reincarnates!
There are 3 types of spirit: harmonic, dissonant, fallen
The harmonic spirit. The spirit that start its journey from a low state spirit and progressively grows.
State 1 - Plant
State 2 - Animal
State 3 - Human
State 4 - Giant
State 5 - Demi-gods
State 6 - Gods
The dissonant spirit. The spirit that does not have the harmonic process. It lacks the multitude of years of intuition and experience. It is known as the empty spirit.
How such a spirit is born?
When the soul dies, the spirit leaves the body. But maybe the body could be brought to life. If the body is not damaged, the mind might awaken. A soul needs a spirit! So, the body and mind creates it!
The mind has the memory and the abilities. The body has the place where it could be born. That person might be the same, but it might feel strange. It might not recognize its friends as the original spirit did. Something is missing.
Or by intent.
A body and mind could be created! And the birth of the unnatural can begin!
The fallen spirit. This information is not available.