Naturally, I Demand Restitution!

Histoire

"I hereby void our engagement!" My name is Yuriath, daughter of Count Noggar, and my fiance, the son of a Marquis, has just announced the end of our betrothal. All this because my now ex-fiance is smitten with Julie Vanash, the common-born illegitimate daughter of a Count, who recently transferred into our private academy. She's convinced that she's the star of a popular romance series, and has cast me into the role of the "jealous and haughty villainess".... Truth be told, the engagement itself was just business, so I have no lingering attachments to my fiance.

Synopsis via AniList (en anglais).