Introduction In the war between humans and demons more than 2,000 years ago, in order to protect human beings' living space, the good and the evil were forced to join forces, and they won at a heavy price. As a condition of existence, the monsters in the world were sealed in the demon barrier. After that, the alliance of good and evil disintegrated, and they faced each other again. The lord of the demon world, Ba Tian, conspired to break the barrier in order to see the light of day again and turn the world upside down. Two worry-free young men were forced to be involved in the conspiracy. A handful of Xuanyuan, a lifetime of love, and a lifetime of hatred and entanglement. . . . .