In this world, there is a division between Yin and Yang, with the living in the Mortal World and the souls in the Underworld.
However, the Yin and Yang Realms are not just differentiated by souls, but also represent a bifurcation of the world, split into two layers, mirroring each other like a reflection, one inside, one outside, influencing each other yet distinctly separate.
Ordinary souls, after death, naturally enter the Underworld and rarely return to the Mortal World, let alone interact with living souls.
This is also as it should be, given the harsh living conditions of souls, if they truly shared the same realm as humans, incidents of evil spirits eating humans would be hard to prevent, even with deities above, it would be difficult to eliminate completely.
