Its a way to buy items on Yahoo Auctions Japan. Going via their site displays translated pages.
You need to setup an account first. Then they need credit card details up front, with an agreed deposit (not actually charged) allowing you a set bidding limit. You bid via the Rinkya site for the item on Yahoo Auctions that you are after. It can take a day to up your bidding limit, so make sure you know how much you want to spend beforehand.
You will get charged commission for the final price if you win. This only buys you the item and gets it delivered to Rinkya's warehouse in Japan. If you want it shipped, you need to pay shipping PLUS a Rinkya handling fee.
The final price can come in at nearly twice the final bid price.
Rinkya won't ship certain automotive items. Full details are on their site. Full fee details are also there.
Yep. I would generally only buy through them if I REALLY wanted something and couldn't get it here. In this case, just bid and win. They'll take payment and commission and will do the rest. They'll tell you when they have the item, then you ask them to send it. Again, they'll take payment and send it. The one thing I bought took ages to be sent to them. You have to allow about four weeks for something to arrive with them before chasing it.