Saihate no Paladin S01

In a city of the dead where it has been centuries since the last human lived, a boy named Will lives. He is being raised by three ghosts: a passionate skeleton warrior named Blood, a beautiful mummy priestess named Mary, and a moody ghostly wizard named Gass. The three of them love the boy and teach him everything they know. But one day, Will starts asking: "Who am I?" Will has to uncover the mysteries of the remote land of the dead and discover the hidden past of the ghosts. He has to learn about the love and mercy of the good gods, and the hatred and madness of the bad ones. And when he knows everything, the boy takes his first step to becoming a hero.