The king of the underworld, a demon cat, comes to our world to prevent the incasion of demons.
He meets the descendants of his human friend (it seems he liked him a lot), a taoist priest who was defending from the human world. Onky a few days passed in the underworld, but 3000 years in our world.
The last descendant never believed his grandfather's stories. But he gave him some of his family powers to fight the demons with the king.
Chapter 26
Cat & Sword