Instructions
Go to the logo on the far left of the XMB -- or cross media bar -- to create a new local user. Log in as this new user, then scroll over to the PSN icon on the XMB, and select "Sign Up for Playstation Network." Select "Create A New Account," then "Continue."
Change your country of origin to "Japan." This will change your language to Japanese. Put in your birthday, and select the blue button on the far right at the bottom to continue. Scroll down to the bottom of the next screen, then click the blue button on the far right at the bottom to accept.
Enter the information on the next screen in descending order: e-mail address, password, password confirmation, check box for saving the password, security question (leave as default) and security answer, which can be any easy to remember word. Select the box at the bottom far right to continue.
Enter your PSN ID, and select the box at the bottom far right to continue. If you get a screen with an "OK" button, your ID is fine to use. If you get another screen with no "OK" button, press the circle to input another PSN ID. Enter whatever you like on the next three screens for contact and address info. On the last screen, which recaps your information, select "Confirm" on the bottom to create your account.