I Build an Underworld, and It Makes Sense to Be the Ghost Emperor, Right?

Bai Yu accidentally traveled to the underworld, only to find that this underworld was completely different from his previous life. This place has just experienced a catastrophe. The masters have fallen, the beasts of the underworld are rampant, the order is chaotic, and the power of the underworld has declined. There are cultivators in the world who enter the underworld at will to modify the book of life and death. There are underworld beasts that kill and devour the ghost spirits and ghosts and treat them as slaves. The specifics are this. Onmyoji: I have unimpeded access to the two realms of yin and yang. The underworld is just my back garden. Monk: Kid, bring me the book of life and death. I want to live another five hundred years. Buddhist Cultivator: This ghost dares to capture my soul, so I need to save him first. Beast of the Underworld: I, the Twelve Heavenly Beast Clan, dominate the underworld, and the creatures of the underworld will always crawl under our feet. Until Bai Yu awakens the Ghost Emperor Development System and obtains the Emperor Sword, the Eye of Tongyou, and the Nine Nether Mysterious Heavenly Yin Emperor Technique, the underworld will change. Bai Yu: So it doesn't matter if the underworld is weak, or if all the high-level officials are lost. From now on, those who openly commit crimes against the underworld will never come back, and there will be no wronged souls under the emperor's sword. Those who commit crimes in embarrassment will be punished on the spot; those who act against the law will be executed without mercy; those who invade the underworld will have their bones shattered and ashes thrown away. Set up ten halls of Yama, build six paths of reincarnation, stabilize the two realms of yin and yang, build nine hells, monitor the yang world, and suppress the underworld. Let's see how Bai Yu builds a brand new underworld.