I have yet to see substantial evidence supporting any reason why they couldn't.
The question KoM isn't whether or not you
can sail from Japan or China to the Americas, the question is that there is no reason
for them to do it, quite a lot of reasons it would be ridiculous, and no sign of any concern on the part of, as Flubber put it, the Usual Suspects to acknowledge the difference between Europe's situation (where "sailing West in search of better routes to Asia" makes a lot of sense) and China's or Japan's or Korea's (where sailing East into the unknown makes no such sense).
- People who would want to pull it off are able to without any restrictions from the state.
People who would want to pull it off are missing.
-The Shogun could order it, Wealthy Nobles or Merchants could organize it.
-Crossing the Pacific bad been done several times at this point from both directions. Something which seemed to be common knowledge or obtainable knowledge if Drake did it.
-Competition by Chinese,Korean, Indonesian, and/or European merchants and navies makes expansion westward an southward untenable.
Drake doing it does not make it common knowledge in Japan.
More untenable than a voyage into the bloody unknown where there's no reason to think that there will be something worth the expense on the other side except
rumors and
hearsay?
God's stinkin' gym socks man, who in their right mind is going to launch an expensive expedition on that?
-Japan has the technology and resources to have oceanic ships with the supplies and manpower to crew them.
-The Americas are already discovered. The image being that people that go there find gold and wealth alot.
So much for "East Asian
discovery of the New World", but okay, fine. And the areas where gold and wealth are found are already under Spain's control, and the idea that because "there's gold here, therefore there's gold elsewhere" is wishful thinking.
Not utterly impossible, but not really desirable, either.
-Knowledge of local currents would set the bar low, having ships follow the Pacific Current NorthEastward into the North Pacific Current. Sweeping along the coast of California. Making several trips on land. Even being attacked by wolves. Noting the lack of development amongst the locals.
-Expedition to Japan returns via the equilateral current, being pushed slightly south of Japan they sail north to home. Backers are disappointed by lack of gold, but determined to discover it.
Backers are disappointed by lack of gold, disappointed by lack of any other results, and wonder why they should fund another expedition.
And this is ignoring the issues with just following the current - nevermind any dangers of running out of food or water because this is Civilization where you just need "shields".
-News of the expedition and likely the route and details spread via word of mouth.
Including its failure to find anything that justifies the costs!
-Expedition returns. Disappointment at lack of gold. Whoever financed all this realizes they are in too deep. They have to find profit somehow. One of the dead animal skins brought back by the sailors is noted to be very water resistant and possibly fashionable. Knowledge of the Americas spreads further in Japan with rumors good and bad spreading.
Given the Japanese social stigma about working with animal skins, this underlined part . . . is rather remarkable.