Getting a Mobile Phone in Japan as a Foreign Resident: Phone Numbers, SIM Contracts, Carriers and MNP

A Japanese mobile number can become part of daily administration long before it feels like an ordinary communication tool. Banks, landlords, employers, delivery companies, hospitals and online accounts may ask for a reachable domestic number. The difficult part is not simply buying data. It is choosing a service that supplies the type of number, identity verification, payment method and device support needed for long-term residence.

Japan has several contract routes: a major mobile network operator, a lower-cost mobile service using another network, a prepaid or short-term product, and a data-only travel eSIM. They are not interchangeable. A plan designed for visitors may provide data but not a standard Japanese voice number, while a conventional voice contract can require current address records, identification and payment screening.

Quick Decision Table: Which Type of Mobile Service Fits?

Decide Whether You Need Voice, SMS or Data Only

A mobile plan can provide three different functions: ordinary voice calling, SMS and mobile data. Do not assume that every eSIM includes all three.

• Voice service is needed for ordinary calls using the assigned mobile number.
• SMS is frequently used for verification codes and account recovery.
• Mobile data provides internet access but does not by itself create a normal voice service.
• Internet calling apps depend on data and do not always replace a domestic mobile number.
• Emergency access should never be assumed on a data-only product; confirm the provider’s stated capabilities.

What to Prepare Before Applying

Complete address registration before applying whenever possible. The practical steps are covered in our resident-registration guide.

Identity Documents and Address Matching

Each provider publishes its own list of accepted documents and application routes. A residence card may be accepted, but the provider can also require a passport, supporting address document or a particular verification method. Online and store applications may use different processes.

Check all of the following before submitting:

• The name is entered exactly as required by the identity document.
• Roman letters, middle names and spacing are consistent.
• The current address is recorded on the accepted document.
• The document is unexpired.
• The front and back are submitted when required.
• The photograph and document number are readable.
• The contract holder and actual user are identified correctly.
• A representative has the required authorization documents.
• My Number itself is not exposed when only an identity document is requested.

Rakuten Mobile, for example, warns that the application details must agree with the identity record and that verification methods can vary according to nationality. Docomo, au and SoftBank also publish separate identification requirements rather than one universal industry list.

Service Contract and Device Installment Are Separate Decisions

A mobile line and a financed handset are not the same contract. A provider may accept a SIM-only service while declining or changing the conditions for installment purchase.

Carrier guidance shows that a separate credit or installment agreement may be required. The remaining period of stay can be relevant when the planned installment term extends beyond the verified period of stay.

Compare Contract Types Without Relying on Advertised Price

Do not compare only the first month or campaign price. Compare the ordinary monthly cost, data allowance, call charges, optional packages, device payment, SIM fee, support and cancellation consequences.

Full Cost Checklist

Prepare a Reliable Payment Method

Providers may accept a credit card, bank debit or other stated method, but the available choices depend on the service and application channel. The payment account commonly must belong to the subscriber.

Before applying:

• Check whether an overseas-issued credit card is accepted.
• Confirm that the card name matches the contract holder.
• Ask whether bank debit can be registered immediately.
• Check whether a temporary payment method can later be changed.
• Keep enough balance for delayed first billing or combined charges.
• Review the first bill for unexpected options.

Our Japanese bank-account guide explains the address, name and payment issues that frequently appear during account setup.

Bring Your Own Phone: Compatibility Checks

Carrier pages for using devices sold by other companies make clear that network connection and complete operation are not guaranteed merely because a SIM physically fits.

Physical SIM or eSIM?

An eSIM can reduce delivery time, but it requires a compatible phone and a reliable activation process. A physical SIM can be easier to move between compatible devices, although delivery or shop collection may take longer.

Check:

• Whether the exact phone model supports the provider’s eSIM.
• Whether the phone is already using another eSIM profile.
• Whether a Wi-Fi connection is needed during activation.
• How the profile is reissued after loss, reset or device replacement.
• Whether switching between physical SIM and eSIM creates a fee.
• How identity verification is completed before activation.

Getting a Japanese Number Before Bank Setup

The order can feel circular: a bank may ask for a telephone number, while a mobile provider may ask for a Japanese payment method. There is no single solution accepted by every company.

Possible routes include:

1. Use a provider that accepts an eligible credit card without an existing Japanese bank account.
2. Choose a temporary voice service that provides a usable Japanese number.
3. Apply for a bank account that accepts your current contact arrangement.
4. Move to a longer-term mobile contract after the bank account is active.

Verify that the temporary number can receive the specific calls and SMS messages you need. A data-only travel eSIM does not solve the phone-number problem.

For a brand-specific example rather than a market-wide recommendation, see our Mobal Japan eSIM and Japanese phone-number article.

Keeping Your Number With MNP

Mobile Number Portability allows an eligible Japanese mobile number to move to another carrier. The practical procedure depends on the current carrier, new provider and application channel.

Changing Carriers Without Losing Account Access

A phone number is often connected to banking, email recovery, messaging apps, delivery accounts and two-factor authentication. Prepare before switching.

• Back up contacts, photos and authentication data.
• Confirm access to the email used by both carriers.
• Record the old carrier account ID and PIN.
• Check whether carrier email will stop.
• Review device installments separately from the line.
• Confirm that the new SIM supports the existing phone.
• Keep another internet connection available during activation.
• Test incoming and outgoing calls.
• Test SMS verification.
• Test mobile data away from Wi-Fi.
• Update services only when the number actually changes.

Why an Application May Stop or Require More Documents

A delayed or unsuccessful application does not always mean that foreign residents are categorically ineligible. The cause may be a specific mismatch or a separate device-financing decision.

Door-to-Door, Telephone and Unrequested Sales

Do not provide identity documents, bills, one-time codes or account credentials merely because a caller claims that your network must be changed.

• Ask for the legal company name and seller’s relationship to the carrier.
• Confirm the offer using the carrier’s official website or shop.
• Request the complete contract and normal price in writing.
• Check whether a handset, option or home-internet bundle was added.
• Do not accept a false claim that the current line will immediately stop.
• Seek consumer-affairs help promptly when solicitation appears deceptive.

Consumer remedies depend on how the contract was made and the applicable cancellation system. Do not assume that every online, shop, telephone and door-to-door contract follows the same rule.

Application Conversation Template

Hello. I live in Japan and need a mobile plan with a Japanese voice number, SMS and mobile data.

Could you confirm which identity documents and payment methods are accepted, whether my phone is compatible and whether the plan supports normal voice calls and SMS authentication?

Please explain the ordinary monthly price, activation fee, optional services, device-payment terms, MNP procedure and what I must do when cancelling or leaving Japan.

Useful Japanese phrases:

• Onsei tsūwa-tsuki no SIM o mōshikomitai desu. — I would like to apply for a SIM with voice calling.
• Kono sumātofon wa tsukaemasu ka? — Can I use this smartphone?
• Hitsuyō na honnin kakunin shorui wa nan desu ka? — Which identity documents are required?
• Kono denwa bangō o sono mama tsukaetai desu. — I would like to keep this telephone number.
• Bunkatsu barai dewa naku, SIM nomi keiyaku shitai desu. — I would like a SIM-only contract without installment payments.

Official Sources

• NTT Docomo: New Subscription Procedures
• NTT Docomo: Documents Verifying Identity
• NTT Docomo: Switching With Mobile Number Portability
• NTT Docomo: Using a Device Sold by Another Carrier
• au: Items to Prepare for a New Contract
• au: Items to Prepare for MNP
• au: Using Another Company’s Mobile Phone
• SoftBank: Identification Documents
• SoftBank: Switching With MNP
• SoftBank: Using Mobile Phones Sold by Other Companies
• Rakuten Mobile: Identity Verification Documents
• Rakuten Mobile: Online Application Guide
• Consumer Affairs Agency: Consumer Contract System
• Consumer Affairs Agency: Door-to-Door Sales
• Consumer Affairs Agency: Telemarketing Sales

Accepted identification, payment methods, fees, supported devices, MNP procedures and installment conditions can change. Confirm the current official page for the exact provider and application channel before submitting personal information.

Final Mobile Contract Checklist

• Decide whether you need voice, SMS and data.
• Complete address registration where possible.
• Use the same legal name across identification, payment and application records.
• Check the identity document’s address and expiry date.
• Prepare a provider-supported payment method.
• Separate the SIM contract from device financing.
• Check SIM lock, bands, VoLTE and eSIM support.
• Confirm that the plan provides a standard Japanese mobile number.
• Compare normal cost after promotions.
• Remove unnecessary optional services.
• Use MNP before cancelling when keeping a number.
• Back up authentication and account-access information.
• Test voice, SMS and data after activation.
• Keep the contract, customer ID and cancellation instructions.
• Review the final bill and remaining device balance before leaving Japan.