This study, Japanese Wrecks stranded and picked up adrift in the North Pacific Ocean by Charles Wolcott Brooks, presented before the California Academy of Sciences in 1875, published in 1876, lists on page 10 (among dozens of other entries covering many years) what may have been the relevant encounter in 1815 (emphasis mine):
- Captain Alexander Adams, formerly pilot at Honolulu, relates that March 24, 1815, in latitude 32° 45' N., longitude 126° 57' W., when
sailing master of brig Forrester, Captain Piggott, and cruising off
Santa Barbara, California, he sighted at sunrise a Japanese junk
drifting at the mercy of the winds and waves. Her rudder aud masts
were gone. Although blowing a gale, he boarded the junk, and found
fourteen dead bodies in the hold, the captain, carpenter, and one
seaman alone surviving; took them on board, where by careful nursing
they were well in a few days. They were on a voyage from Osaka to
Yedo, and were 17 months out, having been dismasted in consequence of
losing their rudder.
So it appears three survivors were picked up off the Santa Barbara coast in 1815.
The same page also lists a couple of other encounters you may find of interest.(Russian encounters).
An interesting map showing the related winds and currents can be seen in the early pages.You can see from the flow of these ocean currents how a ship which had lost the ability to navigate (broken rudder and/or masts) could end up either along Kamchatka, Alaska, or even the California Coast.
By the way, to actually answer the direct question, concerning this specific event, it does not appear that they had landed, but were rescued from a ruined ship offshore.