Eris no Seihai ( Eris's Seihai )

In a world where nobles are notorious for their ruthless pursuit of power, one family stands out for their commitment to honesty and virtue: House Grail. The youngest member, Constance Grail, embodies these values, always striving to do what’s right and lend a helping hand to those in distress. Unfortunately, her strong moral compass doesn’t shield her from heartbreak when her fiancé betrays her trust by cheating with another woman. Things take a turn for the worse when Constance is framed by her fiancé's new lover, leaving her desperate for justice in a world that refuses to listen. Just when it seems all hope is lost, she encounters the spirit of the notorious Scarlet Castiel, who has her own vendetta. Scarlet, who was wrongfully executed a decade ago for a crime she didn’t commit, sees Constance as her only ally. With a fierce determination for revenge against those who wronged her, Scarlet possesses Constance, turning the tables on her enemies. But this supernatural assistance comes with its own set of challenges, as Constance must navigate the complexities of vengeance while staying true to her principles.