I remember my mother-in-law once said: "We are demons. We are different from humans in many ways. Let's talk about the reincarnation of life and death. The current Lord of Hell is a weird ghost. When a person dies, the underworld will arrange his next place. But we demons are not good. We cannot make mistakes. Every time we make a mistake, we will stay in the world for one more day. If a ghost stays in the world for a long time, it will only be dispersed."