The Reincarnated Great Saint Hides Herself as a Saint

Fia, who is aiming to be a knight as the daughter of a knight, remembers her previous life as a "great saint" when she was on the verge of saint is currently a highly important and respected profession because of its verge of extinction and the power of saint I can use happened to be the "lost magic" that has turned into a fairy the way, in the previous life, I was threatened by the Demon King's right arm, saying, "I'll kill you again if you're reborn as a saint".If I use such power, I wonder if I would be caught and killed in one it's okay, I have decided to become a knight & live quietly!