Kon'yaku Haki wa Honmou desu! Seijo no Chikara ga Kaika Shita no de Watashi wa Jiyuu ni Kurashimasu ~Honmono no Seijou wa Gishi de wa Naku Watashi deshita~

Lisette, the duke's daughter, is engaged to the crown prince. However, her stepsister who has been glorified as a saint, steals her fiancé and Lisette is banished to the frontier under false charges. She is rescued by the legendary king of spirits, who says that he will take her as his own saint, and discovers that Lisette is in fact the true saint! Deciding to live freely, Lisette uses her awakened saintly powers to cleanse the land of demons, and uses the knowledge and magical powers she has accumulated through her queenly education to reform agriculture. As a result, the desolate frontier suddenly underwent great development! While Lisette's success makes the frontier the most powerful territory, the kingdom is in decline, and the crown prince and her stepsister are in dire straits...?