George Lensen's "The Russian Push Toward Japan" says on pp. 261:
In 1815 the transport Pavel under the command of Navigator's Apprentice Srednii left Okhotsk with six Japanese castaways, three of whom had been shipwrecked off the Kuril islands, the others having been swept to California and brought from there by an English merchantman.
I've not been able to verify this story anywhere else. Did Japanese sailors really reach Spanish California?