You can apply directly from the Data Charge website. The payment methods available are "au Easy Payment" and "Credit Card". Please see the detailed procedure below.
Access the Data Charge website from the link below and tap on "Login with au ID"[au IDでログイン].
Enter your au ID and tap on "Next"[次へ].
Enter your password and tap on "Login"[ログイン].
Select and confirm "Charge Plan/Charge Timing/Charge Frequency"「チャージプラン/チャージタイミング/チャージ回数」, then tap on "Proceed to Payment"[決済手続きへ].
If you want to change your payment method or whether to use points, tap on ①② in the image.
Enter the 4-digit PIN code you set when you subscribed for the contract and tap on "Pay"[支払う].
The data charge procedure is now completed.
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