Is there any practical/technical/security problem with simply printing off and mailing a buttload of cheques to people that request them?
If you cash over ¥ 1,000,000 via cheques you have to specify it with the Japanese customs office. Have fun! In Germany it is partially prohibited to redeem cheques. I have never cashed a cheque from Japan and do not know if that's possible. My last cheque I have got about 10 years ago from my old phone company. I first had to figure out how I can redeem the thing. It was just possible, but unusual.
Really, I think in this case it would be easier to send money via Western Union. Cheques are antique and cheques from foreign countrys are mysterious. I never ever have received something like that.