Best Answer - Chosen by Voters
I think you should start out first by asking the Japanese embassy in your place, and first ask if there are volunteers who work in your country. I don't mean to discourage you, but since living in Japan would cost much, Japanese volunteers are working outside Japan, and chances are if you can't speak Japanese language fluently, you can't be of much help compared to doing help in your own country. Another thing is that, immigration people thinks that not all people are 100% committed in doing volunteer work and that they are just using this as an excuse to find an entry to Japan and later find a profitable job. It is not bad, but if you can speak Japanese fluently, you can even go here on your own and work, and you will learn the Japanese culture. Things that you may find to your liking and maybe some not.
Hope that helps
Source(s):
NGO Japanese friends who worked outside Japan and tried to convince their organization to have some people work in Japan as well..