When Pangu's giant ax split the chaos, there was a secret crack hidden in the roar of the first separation of heaven and earth. The crack is not in the mountains and rivers of the human world, but at the junction of Yin and Yang, like an unhealed wound, greedily filled with the ghostly energy that escaped when the world was created. As time passed by for hundreds of millions of years, the netherworld aura that absorbed the power of chaos in the beginning of heaven and earth actually condensed into a realm independent of the three realms in the intertwined gap between reality and reality - the ghost that was later called Fengdu was quietly conceived in the shadow of this crack.