I'd say your barriers are knowing enough of the language (JLPT3 is probably too low, although even at my own science uni, we take GRADUATE students with little to no Japanese). Since many of them don't actually take classes but do research instead, it's not that much of a bother, but there are many (master's program students) who DO take classes, and they say it's very tough because they don't get much if any language support.