A long time ago, the world was created as one. Different species occupied the same land and coexisted without an issue. Until the disease called death came to be.
Among those that ruled were the angels and demons. It was common knowledge that the two lobes were longer than most of the other species.
Their physiques were unique as was the beauty they possess. Years later, the other species began to covet them. Suddenly, intermarriages were introduced.
These led to the birth of hybrids. It didn't take long to disrupt the harmony in their coexistence. A lot of deaths began to occur.
To save humanity, the realm was divided into two. The angels and demons were left to occupy one part while the rest of the beings occupied another.
The two realms were then separated by the bridge of life and death. If anyone tried to cross over while the bridge was closed, their ending would be worse than death.