Important Note: PlayStation Network Card (JP) sold by SEA Gamer Mall only VALID for Japan registered PSN Account users.
Customers outside of Japan can easily top up funds to your Japan PlayStation Network account without the need of a Japan credit card. Japan PlayStation Network Cards are a great way to add credit easily to your Japan PlayStation Network account.
Use the card to purchase downloadable games, game add-ons, full-length movies, TV shows and other content that you can play or view on your PlayStation 3 or PSP. Code is redeemable ONLY at the Japan PlayStation Store.You will need a PlayStation 3 or PSP (any region) and a Japanese PSN account (free registration, no credit card required) to use the gift card code.
Here is the Playstation Network Card redemption guide in further details.