It's pretty easy to get the visa....I go to Tokyo every year, now they got give multiple entry for 3 years, anyways, there are 5 things you need:

1) The filled up visa application form
(can be downloaded here http://www.my.emb-japan.go.jp/English/visit.html#B )
2) The filled itinerary of your trip to japan (form can be downloaded at same location above)
3) A letter from your employee (with company letter head) stating how your position and year of service
4) Photostat bank book, I always do that, photostat the page with your name then the page with the latest balance, all on one page in an A4 size paper
5) Your flight ticket booking

Just make sure you bring the original, because the staff there will check your original and mark on the photocopies, no need official bank chop or anything, so if you photocopy your bankbook, bring your bankbook along.

I just got my visa last week, i alway go on a Wednesday and you can take back on a Friday, they will give you a receipt telling you what date and time to go collect, normally 3 days