Quick answer
Getting a mobile phone in Japan (携帯電話契約, keitai denwa keiyaku, mobile phone contract) usually requires 本人確認書類 (honnin kakunin shorui, identity verification documents) and a payment method (credit card or bank account direct debit), plus choosing a 料金プラン (ryōkin puran, rate plan). The contract states the monthly fee, the contract period, cancellation-related terms, and whether MNP (mobile number portability) is available. Terms differ by carrier — follow your contract and each carrier's explanation.
What signing up / the contract usually involves
- Choosing a carrier and plan: major carriers (docomo / au / SoftBank), budget SIMs (格安SIM, kakuyasu SIM), and others — rates and conditions differ.
- Preparing documents: 本人確認書類 (identity verification documents) and a payment method (クレジットカード / 口座振替, kurejitto kādo / kōza furikae — credit card / bank account direct debit).
- MNP: if you want to keep your current number when switching carriers, apply for mobile number portability.
- Reading the terms: watch the 契約期間 (keiyaku kikan, contract period) and 解約 (kaiyaku, cancellation) conditions.
Common fields on the contract / bill
- 料金プラン (ryōkin puran) — rate plan.
- 基本料金 / 月額料金 (kihon ryōkin / getsugaku ryōkin) — monthly fee.
- 契約期間 (keiyaku kikan) — contract period.
- 解約金 / 違約金 (kaiyakukin / iyakukin) — cancellation fee / penalty (regulations set a cap on the amount; follow your contract).
- 初期契約解除 (shoki keiyaku kaijo) — a consumer protection system that lets you cancel within a certain period.
- MNP（番号ポータビリティ） (bangō pōtabiriti) — mobile number portability.
- 本人確認書類 (honnin kakunin shorui) — identity verification documents.
- 口座振替 / クレジットカード (kōza furikae / kurejitto kādo) — bank account direct debit / credit card.
- SIM / eSIM — SIM card.
What you need to do
- Compare carriers and 料金プラン (rate plans), and get your 本人確認書類 (identity documents) and payment method ready.
- To keep your number, apply for MNP (you can usually switch carriers without changing your number).
- After signing, check the 月額料金 (monthly fee), 契約期間 (contract period), and 解約 (cancellation) terms in your contract.
- If anything is unclear or you want to cancel, contact your carrier; for consumer protection systems, see the Ministry of Internal Affairs and Communications (MIC) mobile phone portal.
Possible costs / where deadlines appear
- Costs: the 月額料金 (monthly fee), cancellation fees or handling charges, and so on — follow your contract and carrier.
- Deadlines: the 初期契約解除 window (you can cancel within a certain period after receiving the written contract), the contract renewal month, and so on — follow your contract.
Which official body to check with when unsure
Your contract and rates are governed by the carrier you chose; for consumer protection systems such as MNP and 初期契約解除, see the MIC mobile phone portal site; for disputes, call Japan's Consumer Hotline 188. In all cases, the contract and official explanations take precedence.
Common Japanese terms
- 携帯電話契約 (keitai denwa keiyaku) — mobile phone contract
- 料金プラン (ryōkin puran) — rate plan
- 基本料金 / 月額料金 (kihon ryōkin / getsugaku ryōkin) — monthly fee
- 契約期間 (keiyaku kikan) — contract period
- 解約金 / 違約金 (kaiyakukin / iyakukin) — cancellation fee / penalty
- 初期契約解除 (shoki keiyaku kaijo) — initial contract cancellation (a cooling-off-like consumer protection system)
- MNP / 番号ポータビリティ (bangō pōtabiriti) — mobile number portability
- 本人確認書類 (honnin kakunin shorui) — identity verification documents
- 口座振替 (kōza furikae) — bank account direct debit