There will always be evil in the world, but the evil in this novel is something no human should ever have to confront. Only a chosen few can stop it, and the fate of the world rests on their shoulders.
(Based on the prompt. Every generation, a holy maiden, is chosen to imprison the soul of a powerful demon. The maiden must embark on a pilgrimage to holy sites to reinforce her soul and contain the entity. Every demon is out to kill her and free their master. You are appointed as her life long protector.)