A thousand years ago, the demon race and humanity fought one another in a long and bloody war. After years of conflict, a man calling himself the angel Michael appeared. He suppressed the demon race within Xuanyao Mountain and surrounded it with a vast forest, creating a sealing formation.
To keep the demons from appearing in the human world, humanity built a Great Wall around Xuanyao Mountain and stationed troops there for a thousand years. This army, originally called the Demon Guard, is now known as the Twilight Forest Border Defense Army, and has grown to an enormous size.
Humanity has five kinds of abilities, ranked as follows: human arts, spirit arts, immortal arts, ghost arts, and the rarest, extraordinary arts. As of now, extraordinary arts have not appeared among humans for a thousand years.
The bloodthirsty demon race is arrogant and consists of seven species: dragons, sea folk, beasts, demons, ghosts, winged folk, and vampires. Each has its own distinct abilities. Together, they revere Cthulhu, the leader of the sea folk, as their supreme ruler and plot to escape this space.
In 1937, the Fuguo opened the second Demon Realm Gate in its territory and joined forces with the demon race to rule the world.
After eight years of war among multiple nations, the Fuguo and its allies surrendered and announced that they would never open the gate again. The United Nations then registered both gates as world assets and began secretly researching a key that could create another gate beyond the existing ones…
By the twenty-first century, ordinary humans no longer believed demons existed, while humans with spiritual power quietly protected the world.
But all that peace vanished with the arrival of one girl and one boy…
