I am quite literally deaf as a post--I've got about 20% of my hearing left.
This is relevant, bc it takes me orders of magnitude more time to pick up bits of languages. My strategy in
Mexico, for example, involved pencil and paper, because I'm not good enough to lipread in spanish, but I can read and write it adequately.
Anyways, I second YouTube Red or similar, language podcasts saved for offline listening, and
purchasing a good language dictionary. Some have recommended a cruiser's language book--I forget the name, but it's basically just phrases you might need related to
customs and immigration, approaching
marinas,
navigation, etc. I know one exists for spanish.
Also, download foreign language tv shows or movies with captions. The captions aren't always accurate, but they'll be good enough to give you the gist and help you practice listening to colloquial language in action. Very different experience from the carefully enunciated language lessons :-)
Embassies and
government organizations generally have tons of language resources available online, which may be usable offline, either via pdf or mp3 download, or via the 'save webpage' option.
Language learning audiobooks or videos are
cheap, digital, and may be worth it if you want a simple system versus a Frankestein conglomerate of free stuff. The closest I and my husband got to spanish proficient was via an audiobook of introductory spanish lessons we used while
winter road tripping from
Alaska to
Baja California, Mexico. N paid $25, which worked out to about a nickel an hour each.
I'm lucky to have an interesting array of friends--many of whom have been far more successful than I at picking up new languages, because they spent time living in the countries, spent time actually hanging out with locals, and weren't afraid of screwing up. That being said, a lot of my expat friends say the biggest barrier to learning the language of their host country, is getting comfortable within your expat community. You can really see this in cruising life,
retirement communities, even neighborhoods. Discovery Bay in
Hong Kong, for example--a high rise neighborhood of golf carts and expats, separated from the hoi polloi by a
ferry ride across the bay/moat. (Don't get me wrong, I've enjoyed time in DB, but damn, it is a little weird.)
Are you going to Japan?
Good luck (or hard work) (preferably both).