Sonia Carnelian is the only daughter of the Witch of Salvation. However, during the wedding ceremony that was done in accordance with the treaty, the prince breaks their engagement and condemns her as an evil witch.

"In the original work, 'the last boss' will get angry, but I'm not that stupid." Sonia escapes the crisis with the knowledge of "anime" gained by peering into her previous life. And she gets the prince's knight in exchange for the insult.

(Source: Shousetsuka ni Narou, translated)