[Hatredcopter]

You can stay in Japan for 90 days on a tourist visa, and then you have to leave. If you're from the USA, you need to get a work visa to live in Japan. Getting a work visa means you must have a bachelor's degree from a 4-year university. If you are a citizen of another country, one that has a working holiday agreement with Japan, you can get a working holiday visa which will allow you to work without a degree (for a limited amount of time).

But first and foremost, I'd still highly recommend visiting Japan first. I mean, how do you know you want to live there if you've never been there? Many foreigners who come to live in Japan find out that the country isn't exactly what they expected.