Fushi no Sougishi

Fushi no Sougishi tells the tale of a hero destined to slay a princess. In this world, the dead are laid to rest by the Immortal Undertakers, a long-lived race that resembles humans. Leon, a half-breed among them, is the youngest and on his way to complete his final test when his train derails. Lost in the forest, he encounters a human girl. Though he doesn’t recognize her, an inexplicable urge compels him to protect her—even from his own kind, the other Undertakers. (Source: Mangamo) Original Web Manga.