You can complete the procedure through My au.
Please see below for detailed steps.
Enter your au ID and password.
Select the service you wish to process and tap on "Select" [選択].
Check the change timing and the important notes, then tap on "Credit card" [クレジットカード].
Read the important notes and tap on "Next" [次へ] at the bottom of the screen.
Enter your credit card information and tap on "Next" [次へ].
Check the registration details, select the confirmation method after registration is complete, and tap on "Set" [設定する].
You may be redirected to the card company's website for authentication service (3D Secure).
In such cases, follow the on-screen instructions and enter the password registered with the credit card company, or a one-time password and tap on "Send" [送信].
The procedure is completed when you are redirected to the "Application Completed" [受付完了] screen.
In principle, you must register with your card company in advance to use this service.
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