I agree with Petina, you should always (not just Japan) spend some time in another country before deciding whether if you want to try live there or not. What if you went over with everything planned, turned down alot of other oppertunities elsewhere and spent alot of money, then when arriving it turns out not what you expected? (it does happen). And seemingly alot of people think about this regarding Japan.

And also agreed on the residency visa's, long term before you could apply (10 years total, 5 years working, according to source read), have sponsership, no criminal record and also proof that you have contributed to Japanese society. Being a Assistant Teacher or Singer will possibly be rejected for application while being a Scientist or Engineer wont. Also these applications are looked through more thoroughly than normal visa's and more difficult to get.