I have bought from the seller of Item #160264920103 (j a p-jun) (had to put some spaces or else it would auto change to japanese, hmm..) a few times. No problem at all. He is from Japan.
I know item #360073874438 seller (pcpowercomic) actually has 2 retail outles, but I have not bought from them through e-bay before. They are in Hong Kong, not Japan.
For Japanese Pokemon single cards, I have also bought from BrianJapan (both on and off e-bay), he is on holiday till July 30, 2008 though. He did say he will have some 2008 movie sheet when he comes back. He may not be the lowest priced but he is very nice, package his stuff well, always tries his best to answer questions and never over-charge shipping unlike some other seller who tries to re-cover e-bay listing fees by charging us high shipping fees. I have ZERO problem and 110% confidence in Brian. I think he advertise on Pokebeach's home page as well. He is American and currently living in Fukuoka-Shi (City of Fukuoka in Fukuoka province).