Lady Demirka is a Tough Villainess: the mentally invincible princess crushes the prince’s request to break off an engagement!

Lady Demilka of the Grandched Ducal House is a flawless beauty, intelligent, and possesses an unshakably strong mind—truly the ultimate noble lady. Since childhood, she received elite education as a candidate for crown princess and never doubted she would marry into the royal family. But when the timid prince unexpectedly rejects her, she should be heartbroken... Except she's not. With perfect composure, she boldly moves to crush the broken engagement!

(Source: Comic Zenon, translated)