A few points I’d like to add:

Instead of getting hired by one of the big language chains before you arrive (this is increasingly difficult and I’ve heard some horror stories) another option is the working holiday visa. This unfortunately isn’t an option for people from the US, but if you are from the UK, Australia etc then it’s a very easy way of entering the country.

I first came to Japan on a working holiday visa, and after a year I was on a full working visa. I didn’t have to leave the country either, that law was changed a couple of years ago thankfully.

For renting an apartment you’ll pretty much always require a Japanese guarantor. Plus you have to pay key money, deposit, fire insurance, cleaning fees, and if you have tatami mats you’ll have to pay for them to be replaced too. Renting in Japan basically sucks! Expect to pay about 250,000 just to move in to a standard apartment in Kansai.

As Neil said, many companies worm their way out of getting you national insurance. Don’t let that mean you go without though. I’d recommend getting yourself on the national plan (国民健康保険) ASAP if you company doesn’t do it for you. If you don’t sign up then you will be liable for back payments later for up to 5 years! That could work out to be seriously expensive. Luckily for me, I moved prefectures which wiped out my back-payments and then signed up!
Tim´s last blog ..Spring Party!