Motorcycling in Japan

There's been a couple good sales recently for flights from the US to Japan (~$500 round trip or so) and I've been thinking for a long time to go on a motorcycling trip in the late summer or fall when the weather is the warmest. I've long dreamed it would be a great way to have fun crossing the country without the expensive trains and beaten paths.

The plan is to fly in with my gear, buy a motorcycle for ~$1000 US, and go around for 5-6 weeks with breaks in major cities to explore before selling it. Something around 250cc should be plenty powerful for transportation as well as reliable and hold resale value. I've been on long trips like this before like when I drove from the UK to Mongolia -- and also in the past I've visited many other countries in Asia. That said, I could use a loooot of advice. Can anyone speak to how the process works for buying, registering, and insuring a motorcycle as a foreigner in Japan? What are some of the best spots to visit or camp at?

I've been floating the idea with some Japanese friends I've hosted in the US and am starting to practice speaking the language to get a solid 5-6 months knowledge in.

I'm also very interested to hear any input about travel in Japan.

Anyone want to come along?!

Thanks!