Yakutatazu to Iwareta node, Watashi no Ie wa Dokuritsu Shimasu!

Synopsis:

Flora, the daughter of the western frontier’s margrave, returns from the battlefield only to learn that her fiancé wants to break off their engagement. She doesn’t particularly care—but what does that idiotic prince mean by calling her “a worthless nobody from a backwater margrave’s family”? As troubling signs of a conspiracy begin to surface at court, even graver news arrives: demons are invading her territory.