Once the Epigaea Empire was free of evil, but that prosperous past has since decayed into a desolate future.

When a Fiend, a monstrous soul forsaken by the gods, destroys his village and slaughters his family, Reiner loses all hope of his peaceful future. Traveling the deserts of his region, he meets Tsumugi, an elderly man from the eastern stretches of the Epigaea Empire. Though vitriolic, they build a rapport from their mutual loneliness, and Reiner is enlisted by Tsumugi to become a Saint, a crusader who protects the world from Fiends, among the many other threats to their empire. Suddenly, a young boy with no special training or attributes is a paragon of society. Though deep out of his element, and often overshadowed by far more talented and worldly peers, Reiner remains determined to pursue excellence and become a Saint strong enough to bring his world back to its long-forgotten paradise.