The fox demon Bai Xihe, who had lived for thousands of years, was seriously injured by his enemy when he ascended during his last tribulation, and his inner elixir was broken into two halves. Half of it was still in his body, and half of it fell into the little Taoist nun's body by accident.
Bai Xihe, who lost half of his inner elixir, was shaped into an eight-year-old boy with a yellow mouth when he first cultivated his human form!
In order to get back the inner elixir, he had to approach the little Taoist nun.
From then on, demons, fairies and demons kept coming and going around the little Taoist nun.