The high-ranking powers of the Underworld System included the Five Directions Ghost Emperors and Great Emperor Fengdu.
Then, in the mortal world, "Houtu" established the Great Emperors of the Five Sacred Mountains and the Great Emperor of Earth Officials.
Moreover, in terms of orthodoxy, the mortal world ultimately surpassed the underworld by far.
After all, the ghosts of the underworld retained only the power of their True Spirits... while the living beings of the mortal world still possessed the material power of their physical bodies.
The underworld was ultimately only a temporary waystation in the cycle of life. It could serve as a place to stay for a while, but it should not become eternal.
The dead would eventually reincarnate and welcome a new life in the future.
It was just that there was no way around it for now... The world, the era, and its accumulated contradictions had grown too great. If people could not afford to buy houses, they could not be left unable even to rent one. Thus, the construction of the underworld had been temporarily strengthened, doing its best to make renting and purchasing equally viable and ease the contradictions.
Special times called for special measures, so the Underworld System had been reinforced.
However, while strengthening it, one still had to keep one's gaze fixed on the distant future. "Houtu" was not short-sighted either... Thus, although the Great Emperors of the Five Sacred Mountains had been established, their authority covered an extremely broad range. Intervening in the Underworld System was only one part of their duties, used to prove the orthodoxy and demonstrate the mortal world's authority to command the Underworld System.
After all, Nuwa needed to conquer the world through the living!
In conquering the world and attacking the Heavenly Court, she could not rely