Turns Out I'm so Invincible

Fanmu traveled to the world of immortality, but he could only be an ordinary mortal, living in seclusion in the mountains and forests. Little did he know that his cat was actually a glutton, capable of devouring the world in one gulp. His cow is a great demon king who stomps his feet and shakes the world. He looks like he has no cultivation, but he is actually invincible. Well! I don't know, I'm invincible.