Addressing a couple of earlier queries whilst being too lazy/ignorant to quote multiple people:
Level of Japanese required to get a job in Japan:
- None to beginner : English teaching jobs and not much else
- JLPT level 3 to 2 : Opens the door to jobs for which Japanese is not integral but is important for ease of interaction with other staff and such, e.g. proof-reading, some re-searching jobs, international marketing/promotion (remember the Japanese language proficiency test's lowest level is 4, the highest is 1 which would take a long time to attain)
- JLPT level 1 : Required for interpreting and translation and sometimes for jobs requiring direct interaction with Japanese customers
There are far more opportunities (outside the English teaching realm that is) in Tokyo and Osaka, and to a lesser extent, other major cities. Landing a good job will require research and some initiative.
Check out
http://www.tempuniversal.co.jp for a few example jobs (limited to a few industries though) and what level of English they expect. For some jobs the reason they want to know you are semi competent in Japanese is so they can believe that you will be comfortable and capable in Japan and the office in general. Not necessarily because the job requires it.
I'm going for level 4 in the Japanese test by the way. I'm already well above the requirements for it and it should be easy. But level 3 is probably beyond my ability, at least by December. And the jump to level 2 is huge. Level 4, however, only requires 80 odd kanji (chinese characters) plus hiragana and katakana (phonetic characters) combined with about 800 words and some basic grammar.
To anyone learning Japanese, don't let the written language intimidate you. In my experience you can never learn a language well if you don't integrate your spoken language with an ability to at least read (if not write). Kanji are difficult to begin with but it gets easier and easier to learn more and they have slowly become useful in my thinking and understanding of Japanese even for conversation.