In the midst of feudal Japan, Isabellae Ashiwara, the fiercely independent daughter of a Celtic witch and a samurai master, roams the countryside with her father's ghost at her side, earning her living as a highly-skilled bounty hunter while searching for her long-lost sister, Siuko. Acquiring a misfit crew along the way, Isabellae battles against evil both worldly and supernatural, inching ever closer to discovering the truth of her haunted past...