You can check your au Hikari contract information on My au (Web).
Please see below for detailed instructions.
Tap on "Internet & Phone" [インターネット・電話].
You can check the "Basic contract number" [基本契約番号] and "Next renewal date" [次回更新年月] on this screen.
If you want to check the application date, Tap on "Check / Change Contract Details" [契約内容の確認・変更].
Tap on "Check Application Details" [お申込内容の確認].
You can check the application date from the "Application Information List" [お申し込み情報一覧].
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