It only shows me options in USD. Bonds would be an option, but I play an UIM only, and gathering the funds for this might be... Difficult, lol. Amazon JP has a page for membership, but it is disabled for some reason.
Do you have a credit or debit card issued by a Japanese bank? You can add this card to PayPal and allow PayPal to convert the currency for you. PayPal will charge a small fee for this (around 3% of the purchase).