Out of the blue... and into the green.

I thought it might be useful for some to see what they can expect to have to do when trying to buy agricultural land (nouchi - 農地) here. There are probably other posts scattered around the threads on GP (the best on-line place to meet other foreigners doing similar stuff) somewhere, but maybe people could post links to other relevant info in the comments below this post.

Caveat Emptor: I'm not a lawyer! This is info that I have gleaned by buying agricultural land myself. There may be inaccuracies or missing info amongst the text here. Please check all this for yourself!

Primer: Dividing the land.

Land in Japan is zoned. The first layer of zoning is when land is designated either 区域内(kuikinai)／区域外(kuikigai). This means that such land is either within or without the area that the local municipality defines as the 'urban area'. Laws are comparatively strict if you're buying/building within the urban area.

Within each of the above definitions are the four classifications known as 原野(genya)、山林(sanrin)、農地(nouchi) and 宅地(takuchi). Loosely translated as 'wilderness', 'Mountain Forest', 'Agricultural' and 'Residential'. So it is possible, though unlikely, to have wilderness within the urban zone for example.
[Note: There are in fact a dozen or more classifications of land other than these, but as an individual looking to live in the countryside, the above are the terms you are going to be running into most often. For more info see: Land Use Control Regulation in Japan, or find English translations of J law here.

If you're still reading, what you are probably thinking of doing is buying a plot of land in the countryside. I'll stick to describing the process for that.

Scenario 1: You buy an old Japanese house to do up or use as is.
Your house will either be in the 区域内(kuikinai)／区域外(kuikigai) zones. If in the 区域内(kuikinai) zone, any modifications you make to your house 'should' follow rules for such things as earthquake resilience, Electrical standards and the like. If it's in the 区域外(kuikigai) zone you are more free with what you can do. Your house is also probably registered as 宅地, and you will therefore have an address that is registered at the city office and the land's boundaries will be officially and accurately recorded in both metric and traditional J units of measurement. You will be being taxed at residential rates, and basically doing everything 'by the books'. However, many older houses are built outside the urban area (区域外) and some of those are built on 原野. If this describes your case there are several things to be aware of. Firstly, all land on which houses have been built 'should' be re-zoned as 宅地. This is a legal obligation. This is also often ignored. Particularly with houses that have been standing since before the war when much of this legislation was formulated. If your house is on 原野and is 区域外 the ownership transfer may well be very tricky and if not sorted out carefully (and at no little expense) you may end up paying for and occupying someone else's land. Be warned!

Scenario 2: Buying land to live and farm on.
There's a classic catch 22 situation regarding agricultural land in Japan. You can't buy it unless you are a registered farmer. Of course, you can't become a farmer without farmland... ok. You can see where this is going, right?

There is a way around it though! Rent farmland and make your application to the 農業員会 (nogyouinkai - farmers' association) as a tenant farmer. If accepted (and this is in no way a given) you will be legally able to buy the agricultural land that you've found.
So, how to become a member of the inkai? You should be able to get the necessary forms (forgotten their names) from the municipal office or possibly from a JA office. Along with these forms you will be required to present a written description of what you are going to do there, why you want to do it in that particular place and most importantly, how you intend to make a living while doing so. Of course, your living must be seen to be coming from the land in question. In other words no hobbyists.
Let's face it, unless you're one of the 1% of people with enough savings to live the life of luxury and not have to work to do so, you'll be needing a business plan anyway. Translate the whole thing into Japanese and submit it along with your application. I found these great links that may help you get an idea of the format which is expected. link 1, link 2.
If you're buying through a real estate agent (不動産屋) they should have a scrivener on the books who can make sure you dot all the 'i's and cross all the 't's correctly. Make use of this fella or find your own if necessary! Expect to pay around ¥100,000 for this service.

Changing bare 原野 or 山林 to another classification is not so difficult nor so expensive. However, changing 農地 to another classification, especially to 宅地, is a different ball game. To change agricultural land to residential land requires a minimum area of land to be in your possession (this can, if you're lucky, include rented land). This area of land varies from district to district, but is typically 5 tan (5反= 4,958m² = 1500 tsubo). You will probably only be allowed to change in the region of 100~150 tsubo of this to residential land. Which should be enough. Again, employing a scrivener to do the paperwork is the way to go. Expect to pay in the region of ¥400,000 for this service and fees.

Bear in mind that it is rare but possible to be called for an interview with the inkai. Also bear in mind that it is within their rights to refuse your application.

So far, this is what I've learnt through experience. I'll add more as time goes on. For now, I'll leave it at this. Good hunting!