Duel At Kitanoji (Usagi Yojimbo, book 17)

Duel At Kitanoji (Usagi Yojimbo, book 17) by Sakai, Stan. paperback edition. ISBN: 0761568106664.

Nothing comes easy for rabbit ronin Usagi, not even being a spectator at the planned duel between his former teacher Katsuichi and Katsuichis former rival Nakamura Koji. Before the duel even begins, Usagi becomes embroiled in a dispute between Koji and a local fencing school that demands the samurai challenge its master. Along the way, Usagi discovers a devastating secret - a weakness in Kojis style. Its a secret that could save his teachers life, but at the cost of his own honor.