Some planets are born with natural spirit charm and will nurture all things, giving rise to a natural Star Array.
The Underworld is the other side of the Mortal World, where the laws of Heaven and Earth differ slightly. The greatest feature is the extremely compressed distance between stars, making it the best path for traveling among the stars.
The origin of those strange creatures in the Underworld is unknown even to this small god; it is only known that after all living beings die, their souls return to the Underworld, where they are devoured by these things.
However, planets with spirit charm, their Star Array will simultaneously cover both the Underworld and the Mortal World, forming a cycle of Yin and Yang, endlessly growing. But this also attracts the mad attacks of the strange creatures from the Underworld. If the array is breached and souls devoured, over time, the entire planet will gradually wither and die.
