Chu Xiyun and her best friend Shu Yuwei accidentally rescued a little black cat on their way to school. The little black cat turned out to be a cat demon boy from another time and space. Not only can he communicate freely with humans, he can even transform into a boy with cat ears and a tail that looks like a human. At the same time, the cat demon discovered that Chu Xiyun, who saved his life, was actually a new cat demon who had just completed nine reincarnations. Then she was brought back to Youyu, another cat demon space besides the universe, to look for the antidote. The antidote, the lotus bud, was too seasonal, so she had no choice but to belong to Youyu.
In order to satisfy the unhappy Chu Xiyun's wish, Sui traveled thousands of miles to a different space on Guiyun's prompt, and looked for Shu Yuwei and Ke Yinan, who were both cat demons, in other parallel spaces.
There are more things waiting for them in Youyu...