A permanent resident visa (aka "PR") is the Mr. Miagi black belt of visas in Japan. Why? Well, I'll tell you why:
* Almost all work visas in Japan require some kind of sponsor, usually a company or a spouse. The problem here is that if something happens to your sponsor--e.g. your company suffers a financial crisis, or sweet love turns sour--then your visa could go bye-bye. PR does not have this problem. You're your own sponsor.
* You don't have to renew it every 1~3 years.
* You can get stuff like credit cards and home loans. While it's not impossible to get these without PR, you can enjoy more options and higher credit limits closer to what Japanese citizens enjoy.
* You can work in any industry. Company-sponsored visas usually lock you to a particular industry, but with PR you're free to do whatever you want.
* It's about as close to becoming a Japanese citizen without actually becoming a citizen.
* PR makes you instantly awesome.
As you'd expect, getting something as all-powerful as a permanent residence visa in Japan isn't easy. Unfortunately, it's made even more difficult since the Immigration Bureau's website (esp. the English one) provides very little information as to what's required. Having gone through the process myself, I thought I'd outline it--potentially saving you a headache or two.