My Japanese is limited but...
I'm not sure what u want from that site.. but it doesn't seem like they are taking any online orders at this time.
In general if you want to buy something from Japan you need two things.
1) A Japanese bank account so you can wire money to the seller (Kind of like Paypal.. but direct deposit between individuals. Its a cool system!)
or
a way to transfer money to a bank account in Japan.
2) A method of shipping it. Most japanese vendors don't like to ship things overseas. So you need a third party that is acustomed to shipping things out of country to take care of that for you. (IE. A relative, A friend that lives there, or a company that specializes in that kind of thing)