In the world of Shu Mountain, there wasn't the sort that you find in "Journey to the West" or "Divine Enthronement," where demons could naturally transform into humans once their cultivation reached a certain level.
Beasts in this world needed to work hard bit by bit to achieve a human form, striving to walk upright and evolve their brains and limbs more towards those of a human. Even if their effort reached a considerable level, they would still look like a freak.
To completely become a true human, one either had to cultivate a Primordial Embryo and go through reincarnation, like Hui Zhu, or rely on heavenly treasures to shed their old body and grow a new one, like peeling off one's entire skin to reveal the tender flesh beneath, such as Jin Xunu.
