In the kingdom of Girtonia, the Adenauer family has produced saints for generations. The current generation consists of two sisters who protect the land from monsters and disasters. The elder sister, Philia, is hailed as a prodigy who resolves any crisis swiftly. The younger sister, Mia, while not as exceptional as Philia, has won over the entire kingdom with her warm and endearing nature. Despite their vast differences, Philia and Mia share an unbreakable bond.
Unfortunately, Mia is the only one who truly cares about Philia. Because of Philia's emotionless face and distant manner, her parents constantly reprimand her, and the citizens complain about her. Furthermore, Julius Girtonia, the second prince and Philia's fiancé, would prefer a more sociable bride. As a result, he breaks off the engagement and sells Philia to the neighboring kingdom of Parnacorta, which has recently lost its own saint.
With no choice in the matter, Philia departs at once to serve Parnacorta. As an outsider, she expects to be treated no better than she was in Girtonia. But contrary to her fears, Philia may have finally found a place where she can meet people worth smiling for.