In this chapter, the master of the North Star tells Gaolou that if he wants to become powerful, he has to go north. The three books of Heaven, Earth, and humans are unknown. The book of Heaven's whereabouts is unknown; the book of Earth is already a master. What's left of the three books is the book known as the "Classic of Mountains and Sea" . The master tells him that he should read it and call it "the dark isle" , and then maybe he'll be able to figure out what it is. He also tells him to pass by who is the black knight in the classic of mountain and sea. The black knight is an enforcer, a kind of national security agent. If he gets involved in a classic case involving mountains and sea, he's likely to get into a lot of trouble.