[lmm]

Happens all the time with menial or physical jobs where they're desperate for labour - construction, fishing, forestry, that sort of thing. You can't get a work visa for that kind of job, but if you have a visa for other reasons (spouse, child of Japanese national, etc.) they'll take you.

[petodo]

Yeah, but I assume in that case you don't talk much during the job and don't have really time to talk to practice the language, so it's complete circle - can't learn it in job which doesn't require the language, because there is no reason to use there language. Sure you could learn few phrases or at least improve your comprehension I guess, but I don't think you could get fluent after half year of such (hard) work.