The name of the contract holder is listed in the "Contract Holder Name" [契約者氏名] field, and the contract address is listed in the "Contract Address / Contact Information" [契約先住所/連絡先] field.
I would like to confirm the billing address and billing name
You can check your registered billing address and billing name on My au (Web).
(The billing address refers to the address of the customer responsible for paying the charges. It is used when sending invoices by mail, among other purposes.)
The billing name is listed under the "Billing Name" [請求先氏名] section, and the billing address is listed under the "Billing Address / Contact Information" [請求先住所/連絡先] section.