The four realms are composed of hell, mortal world, fairy world and animal world. Since the end of the ancient war, there has been peace and tranquility. Zhang Yichen took advantage of his father, the King of Hell, to slip into the mortal world and travel around. He didn't know that there was an unwritten rule in the four realms. Anyone who crossed the border without permission would be killed without mercy, regardless of their status. I heard that this rule was set by the God of Ji, the ruler of the four realms in ancient times, so naturally no one dared to refute it. Just when Zhang Yichen was discovered, the King of Hell's righteous intention to kill his relatives shocked a "person" - Ouyang Chuyi. He changed from his normal state and laughed loudly: "Old King of Hell, I'm back." Tens of thousands of years of peace... No one noticed that the seemingly stable four realms had long been covered with a layer of gray.