The Bushido Blade is a fictional sideline to the true events surrounding the treaty Commodore Matthew Perry signed with the shogun of feudal Japan.

The samurai sword entrusted to Commodore Perry for President Franklin Pierce of the United States by the Emperor of Japan is stolen by factions wishing to maintain Japanese isolationism.

The sword is stolen by Baron Zen, who is a servant of Lord Yamato, who opposes the Convention of Kanagawa about to be signed.

Prince Ido has received Hayashi's order to regain the sword and goes to the castle of Yamato alone.

Hawk brings Midshipman Robin Gurr and Crew Bos'n Cave Johnson.