One of the greatest heroines on the surface of Lavato, Cassandra, fights against the evil Galdirea with her dual magic swords: Arken the holy sword and Difora the Soulblade.

But fifteen years ago she was just a little girl, raised by her sister Rosa until a fateful encounter with the evil Ork King Grebados. On the run, she was saved by the most legendary mercenary of the age, Black Dragonfly Francis. So begins her story, and the story of her legendary swords.