+1, especially for parts/accessories. USPS is the carrier of choice, Priority/Express service of choice, easy-peasy-Japanesey. You can do all your shipping/customs documentation and pay for postage online through ebay and/or paypal, waltz into the p.o., get the box scanned and scram. Large items like wheels, frames or complete bikes add a little complexity I think, too large for Priority/Express, size limits exist for Parcel Post, not sure if Parcel Post insurance and tracking are as robust as for Priority/Express. I've shipped heaps of parts to Japan (and Hong Kong, Taiwan and China), I haven't done wheels, frames or complete bikes. If I had a 50-54cm Herse or Singer, or a vintage French wheelset with Maxicar hubs, I'd gladly do whatever it took to include Japan as a shipping location, through USPS.