Received the iTunes card within the time frame as promised. There's some difference in the current registration steps in iTunes Japan, compared to that posted on your site. The process of entering the code comes only during the last step, just before filling the address. The option to click 'none' for credit card only appeared after I'd clicked send without filling the credit card information. Was a bit confusing, but nonetheless suceeded in registering and buying after several failed attempts. So thanks!