Oz Vessalius, heir to one of the duke houses, has just turned fifteen. His life is rich and carefree, darkened only by the constant absence of his father. At his coming-of-age ceremony, however, everything changes. For no reason that he can discern, he's cast into the prison known as the "Abyss", only to be saved by a "chain" known as Alice, the bloodstained black rabbit. It is unknown why was he cast into Abyss, how does Alice factor into it all, and what does the organization known as "Pandora" want with him.
At the beginning of the Edo Era, when people enjoyed a time of peace, Lord Tokugawa Tadanaga holds a fighting tournament. In the past, matches were fought with wooden swords. This time, real swords will be used. One-armed Fujiki Gennosuke and blind Irako Seigen will fight each other in this match. Both are disciples of Iwamoto Kogan, who is known as Japan's greatest swordsman. Each of them are determined to prove himself the successor of Iwamoto's school. However, there can only be one champion. So begins a story of intertwining fates, conflict, and strange destinies.