Tensei shita Daiseijo wa, Seijo de aru koto wo Hitakakusu: A Tale of The Great Saint

Fia, who is aiming to be a knight in a family of knights, remembers her previous life as a "Grand Saint" when she was on the verge of dying. The saint is currently a highly important and respected profession because and is on the verge of extinction! The holy power she can use happens to be the "lost magic" of myths.