You may need to use a VPN when you create a Japanese Apple account.
Go to appleid.apple.com/account.
Fill out the form. *Email must be different from your main Apple ID (if you already have one) or your main email address (in case you plan to have a main Apple ID).
Choose "Japan" from the list of countries.
Fill out the form and submit.
Check your email for verification code.
And you're done.
Other way:
Open iTunes. Sign out of your iTunes account if you are signed in.
Go to the store. Scroll all the way down to the bottom until you see a flag of a country. Click on it.
Select Japan.
Search for a free app, click the app, and click Get.
Note: You MUST search and try to download a free app to have a "None" option for payment when creating an account.
Click Create Apple ID.
Click Continue.
Briefly read and accept iTunes Store Japan’s Terms and Conditions and Apple Privacy Policy.
Enter a clean email address, password, and other details. Click Continue.
Note: You may use your existing Gmail account by adding "+1" at the end (e.g. "example+1")
The Payment Type “None” should be pre-selected for you. Leave the gift card area blank. If it is not pre-selected, choose option “None”.
Input any Japanese hotel address, or use the following
Postal Code: 160-0023 Select “Tokyo” from the drop down box.
Type: “Shinjuku-ku” in the box to the right of Tokyo.
Address: “Nishishinjuku 6-12-6” or anything you want. Leave the rest blank.
Phone: 03 3344-5111
Note the information you used somewhere so you will not forget.
Click "Create Apple ID".
