Eris no Seihai

As a viscount's daughter, Constance Grail is an ordinary girl whose only notable trait is sincerity, leaving her with no real options when someone steals her fiance and falsely accuses her of petty theft at a ball. While Connie awaits her undeserved punishment, a ghost appears to offer a bargain. The spirit is none other than Scarlett Castiel, a noblewoman once praised for her beauty, lineage, and undeniable charisma—and executed some ten years earlier for her wicked deeds. When Connie accepts this proposal, she is possessed by the infamous spirit who instantly turns the tide on her tormenter, thus saving the hapless girl from her miserable fate. It's never wise striking a deal without knowing exactly what you've committed to, though...or you might find yourself bound to a ghost dead set on revenge against her own enemies!

(Source: Yen Press)

Eris no Seihai began as a web novel on Shousetsuka ni Narou on October 16, 2017. SB Creative Corp. released a revised and illustrated version of the series from November 14, 2019, to October 14, 2020, under its GA Novels label.

The series has been published in English as The Holy Grail of Eris by Yen Press since April 19, 2022.