The Holy Grail of Eris

House Grail is an anomalous noble family that prioritizes truth and integrity, setting them apart from their peers. The family's youngest daughter, Constance Grail, embodies these values, but her commitment to doing what's right is put to the test when she's betrayed by her fiancé. Constance is framed for the infidelity and her pleas for justice fall on deaf ears, except for the spirit of Scarlet Castiel, who possesses her. Ten years prior, Scarlet was wrongly executed for the attempted murder of Princess Cecilia; now, she seeks revenge on those who wronged her, using Constance to uncover the truth behind her own framing.