You're up in Tokyo and maybe able to go to a doctor/dentist ofice and ask them for the mnumber of the people tat supply them. I (with my Japanese speaking wife of course, went to pet stores and asked them for the number of the guys that provided their gas for them. Called the compnay as was told that 10,000 yen deposit for the bottle and 5,000 yen refills was all it took to get a tall tank of CO2...worth a try in my opnion. I am in the process of completint my 275 gallon tank set p and will have to eventually do this...for now I still have a 15 pound green coke tank that hasn't been used, but once that runs out, I will start this program. Will keep you posted though I bet you can make it happen before I do...good luck.