Underworld Policy

The Ten Great Yama Halls are located in the Nine Nether Hells. There is also an underworld in the body of the mortal boy Lin Yi. What is the connection between the two? What kind of secrets exist in the Underworld Yin Yang Stone, and who authored the Underworld Policy? Lin Yi, who possesses the "Underworld Policy", throws himself into the fallen ancient sect Donglong Sect, hunts for treasures and practices, and grows into a generation of evil little devil!