[Nyororin]

Under the assumption that you came to Japan legally, for example as a dependent to your parents or a spouse - you would be eligible for a disability allowance if you are eligible for a disability card. However, unless you are at the top tiers of disability, you will not get anywhere near the amount you would need to simply make a living.
It really depends upon the disability. Chances are, you would be eligible for very little as you are able to get online and type that up - in other words, you could work somewhere doing something.

For the common disabilities - Asperger`s receives approximately $10/month. Mild mental retardation about $10/month with transportation discounts. Minor internal "defects" (heart conditions that do not prevent employment, etc) receive no allowance but priority medical treatment, subsidized equipment, and transportation cost wavers. Physical disabilities receive subsidized equipment and an allowance dependent upon how difficult it is to be employed.

There is a disability support center in pretty much every decent sized town offering job placement up until the point where you require total hospitalization. There is very little "living on disability payments" in Japan. Without knowing what your disability is, I can`t really give you more details... My son carries a disability card, so I have all the information on hand though. If you would like to keep it private, you`re totally welcome to pm me about it.

Thing is, if you move to Japan you`ll have to be eligible for a visa - and if you are unable to work the chances of being eligible are very very low.