Shinigami ni Sodaterareta Shoujo wa Shikkoku no Tsurugi o Mune ni Idaku

Olivia is just a baby when the mysterious Z finds her at a temple in the depths of the Forest of No Return. From that day on, the temple becomes her home and Z her family. Z, a god of death, educates her in the ways of the world, in combat, and in the long-forgotten arts of magic—right up until the day Z disappears.