Bought a Japanese iTunes gift card via J-LIST/J-BOX and followed their instructions.
http://www.jlist.com/product/ITUNESCARDBefore you begin, you will need:
1. the 16-digit code from your iTunes card
2. an E-mail address that has never been used in iTunes before.
How to use your card:
1. Load iTunes on your Mac or PC, and choose "Japan" in the iTunes Music Store popup at the bottom of the iTunes Store window. If you've already got an account in your home country, sign out by clicking on the Account button in the upper left hand corner.
**The Japanese iTunes will not work with your home country account, you will need to make a new account. This will require using a different E-mail address from the one you usually use to sign in to iTunes with.**
2. Click the "Redeem" link on the left hand side, and in the box enter the iTunes Music Card number we sent you.
3. Select to create a new account, using any address in Japan you like (you may use ours as a dummy address if you like). You can do this in English or any language that's supported by iTunes -- no need to use Japanese.
a) For Phonetic Name, just reenter your name in English.
b) For Credit Card, be sure to select "none". At this time, it appears that iTunes Japan only accepts credit cards with a matching Japanese address. If you aren't able to get the "none" option for the credit card section at first, check the steps and retry from the Redeem link. We are aware that sometimes the initial attempts may not give you an option for signing up without a credit card, but for some reason when trying again the option appears.
c) For a phone number, Japan phone numbers are three to four digits for the first field, always beginning with a zero. The second field is 7-8 digits (e.g. 060 and 12341234).
4. Enjoy purchasing great music and albums from Japan's iTunes Music Store!
If you like, you may use J-List's address for the registered address of your card. This registration will not and does not entitle J-List to use or listen to your music. This is simply for our customers' connivence. Our address information is:
Postal code: 372-0001
Prefecture: Gunma
City: Isesaki
Address: 4222-3 Hashie-cho,
They don't actually send you the physical card, just the code. So no shipping costs.
Been using them for over a year and a half now. No issues thus far.