Ferris, who comes from a famous clan of swordsmen designated to serve as guards to the King of Roland, is the heroine of the story. She carries a typically emotionless expression, is fanatic about dango (Japanese dumpling) and can do almost anything for the sake of dango.
Ferris is incredibly skilled in the sword and assigned by Sion to guard Ryner on his quest to search for the "relics of heroes". She enjoys teasing and bullying Ryner, and unconsciously gradually develops feelings for him, going into tears then into a berserk rage when she believed Ryner to be dead, attacking an opponent far superior to her with no second thoughts others than vengeance and no thought of her own well being. Her sword possesses the "ability to devour gods", which has the power to cut off the demon within Ryner, but with the price being her own life upon invocation.

She was abused as a child due Her family practicing the dark tradition of incest to keep its bloodline pure. Ferris was originally supposed to marry her brother however Both Ferris and her brother were considered to be unworthy of preserving the Eris bloodline by her parents and would have been killed were not for her brother's murdering of their parents to save Ferris's life and forever ending the Eris's family dark legacy.

She also show signs of being romantically in love with Ryner