[HOWTO] Create a Japanese PSN account on a 5.00+ PSP
1. Make sure you have the latest Official Firmware or latest Custom Firmware. Then go to sign up for Playstation Network. If you are already logged in to a different account then press Triangle and select "delete account".
2. Select "Create a new Account"
3. Select Continue
4a. Change your Country to Japan.
4b. Everything will now be in Japanese, so enter your birthday and select continue.
5. Scroll down the super long Terms of Service agreement and select "Accept"
6. Here's where you enter an email address. You must use an alternate email address, you cannot use an email address that you have already signed up for. gmail is nice and free.
7. Now you have to choose a ID. If you choose an ID that is already taken you will get an error, so choose something unique. After you have chosen a unique ID that is available you'll be able to click the continue button.
8. Now enter you first name, last name, and gender. (they can be made up)
9a. Now you have to enter some numbers. I just entered random numbers until it let me continue.
9b. Next select any province.
9c. Now just enter random stuff until it lets you click on the continue button.
10. On this screen you just have to click continue.
11. Scroll down and click the confirm button
12. Congratulations, you now have a Japanese account and can now download stuff from the Japanese PSN. Just remember, if you are logged into your Japanese account you can only play stuff that is from the Japanese PSN. If you want to play stuff that you've downloaded from other PSN then simple press triangle and delete the account from your PSP. Next just log in with whatever PSN you want to play.
After creating your Japanese PSN account, to download games you have to add fund to your account. You can do this by purchasing a prepaid Japanese PSN card at www.japan-codes.com
They charge you through Paypal. It also has a little bit cheaper price than other site as well.