Tenseishita Daiseijo wa, Seijo Dearu Koto o 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 it's on the verge of extinction! The holy power she can use happens to be the "lost magic" of myths. In her previous life, she was threatened by the right arm of the Demon King, saying, "I'll kill you again if you're reborn as a saint."