Hi there,
I have been in Japan for almost 15 years now doing both photography and graphic design professionally. I can say from my experience that the two most important things I have discovered are to first practice photography in order to get some sort of portfolio going. While working on your portfolio I would also recommend networking with people both foreign and native in Japan. The more you network and build up your photography name, the better chance you will land a freelance and perhaps even a full time job with your photography or graphic design style.
With regards to photography schools there are probably a few around, however they will most likely teach only in Japanese and cost an arm and a leg to join. I personally feel you can do just as well if not better by just getting a great website, namecards, and with camera in hand start shooting as much as possible. Build up your contacts and start making a name for yourself. I find one really has to be aggressive in Japan because the "ingroup" structure is very difficult to penetrate sometimes. However, if they see you are a nice guy/gal and can take great shots, they'll definitely invite you to various shoots.
In any event, if you are ever in Japan, let me know and I we can hook up for a photoshoot. I speak Japanese and am a Street/Location Shooter for both Models and Events.
Enjoy and happy shooting!
Jim Atwood