The human kingdom waged endless war against the Land of Eternal Night where the Demon King lived. The royal family claimed that the devil was cruel and ruthless, and that monsters frequently hurt people because of the instructions given by the devil kings in the past.
However, the Demon King cannot be killed easily. Humans can only pray to God, and the brave men chosen by God will carry God's blessings to kill the Demon King. But new demon kings will always be born, and the reincarnation of brave men killing demon kings will always be staged.
Finally, the new brave Ryan never came out after entering the Land of Eternal Night alone. The Demon King was not destroyed, and God's blessings did not return to the temple, which seemed to indicate the end of reincarnation.
Demon King Linglong: Yes, monsters and humans can coexist peacefully.
Intention: Reconciliation with imperfection