The The Holy Grail of Eris, Vol. 1 (light novel) — Kujira Tokiwa

The Grail family has a single guiding principle in their lives -- Thou Shalt Be Sincere. However, sincerity alone can only get a lady so far in the twisted world of high society...as meek Constance Grail soon learns after she is framed for petty theft and loses her fiancé and reputation in a matter of minutes. But one gaze on her isn't quite as chilling as the others, though the woman's uncanny resemblance to Scarlett Castiel must be a coincidence. After all, Scarlett isn't just extremely wicked…she's also very much dead.