Eh, pirate sails around the world, picks up disgraced samurai who needs to leave Japan. Afterwards they'll sail to England at some point or another, and the thief is looking for passage to America (as a thief he needs to get abroad for a while). They sail over the Atlantic, where they meet the cowboy who's driven cattle from the West to sell at a better price on the East coast.
A call to adventure on top, aaand campaign is a go.