A Japanese phone number is close to essential for daily life in Japan as a foreign resident. It makes bank account setup, parcel delivery notifications, restaurant reservations, municipal paperwork, and SMS-based verification for many Japanese web services significantly easier. If you arrive in Japan without a plan for getting a local number quickly, you will usually run into this wall within the first week.
This guide covers both paths to a Japanese number, the fastest route for new arrivals with no Japanese banking history, eSIM options that work immediately on compatible devices, and how to keep your number when you upgrade plans.
For a broader comparison of data plans once you have your number sorted, see the best SIM card guide for Japan in 2026. For bank account setup — which you will need before the contract SIM path becomes available — the Japan bank account guide for foreigners explains the options that do not require an established credit history in Japan.
Why You Need a Japanese Number
The specific barrier is Japan's telephone number verification system. Japanese mobile numbers (in the 070, 080, and 090 prefix ranges) are recognized by Japanese service systems in a way that foreign numbers, internet calling numbers (050 prefix), or VoIP numbers are not.
Bank accounts: Most Japanese banks require a Japanese mobile number for SMS-based two-factor authentication during online banking enrollment. Some banks will complete the initial application with a foreign number but require a Japanese number before activating full account access.
Delivery services: Japan's major delivery carriers (Yamato Transport, Sagawa Express, Japan Post) send delivery notification SMS messages to the recipient's registered phone number. Without a Japanese number, receiving and rescheduling deliveries requires tracking numbers entered manually on each carrier's website.
Reservations and services: Restaurant booking platforms (Tabelog, Ikyu), medical appointment systems, and government portals including My Number Card applications all use Japanese phone number verification.
Two-factor authentication: Japanese e-commerce, insurance, investment, and government portals predominantly use SMS to Japanese numbers as their second authentication factor. International numbers and 050 numbers are typically rejected at this step.
Path 1: Prepaid SIM with Voice
A voice-capable SIM or eSIM gives you a genuine Japanese mobile number (070/080/090 prefix) relatively quickly. The important practical point is that voice service is verified much more strictly than airport-style data-only SIMs. Expect identity checks and more limited eligibility than with pure tourist data products.
IIJ (IIJmio): One of the most technically reliable MVNO operators in Japan, running on docomo's network. IIJ's voice-capable options can be purchased through major electronics retailers including Yodobashi Camera and Bic Camera. Activation requires identity verification and payment setup. IIJ's BIC SIM counters at Bic Camera locations can sometimes process in-store activation once you have your zairyu card.
Mobal: Specifically designed with foreign residents in mind, Mobal offers English-language customer support and simplified sign-up. Plans are priced somewhat higher than domestic MVNOs, but the English support infrastructure makes them worth considering for the first few months before you are comfortable navigating Japanese-language carrier interfaces. Mobal numbers are genuine Japanese mobile numbers, not tourist VoIP numbers, so they satisfy Japanese service verification requirements.
Path 2: Contract SIM (Postpaid)
Contract SIM plans are cheaper on a per-month basis and come with clearer data allowances, but they require more documentation and take 1-3 days to activate.
Requirements for contract SIM signup:
- Residence card (在留カード, zairyu card) — you must have this before applying
- Japanese bank account or an accepted payment card for monthly billing
- In some cases, a Japanese address that matches your residence card registration
The residence card is issued when you register your address at the city ward office (市区町村). If you have just arrived, this is typically one of the first things you do — registration is legally required within 14 days of taking up residence.
The Rakuten Mobile Path for New Residents
Rakuten Mobile is one practical first contract SIM for foreign residents in Japan in 2026 for two reasons: it is one of the cheapest mainstream carriers, and Rakuten Bank — its sister service — is one of the more foreigner-accessible online banks.
The sequence that works:
- If possible, open Rakuten Bank first. Full details are in the Japan bank account guide for foreigners.
- Once the account is active, use it as the payment method for Rakuten Mobile.
- Apply for Rakuten Mobile online or at a Rakuten shop with your zairyu card and payment setup ready.
- Activate via the My Rakuten Mobile app or through a shop visit.
Rakuten Mobile pricing (2026): The current plan is "Rakuten Saikyo Plan" (楽天最強プラン). There is no longer a free/zero-yen tier. In practice, the pricing starts a little above ¥1,000 per month for light use and scales to a little above ¥3,000 for unlimited domestic data before optional discounts. That still makes it one of the most competitive flat-rate structures among Japanese carriers.
BYOD Compatibility: Japan's Band Requirements
Japan's mobile networks use specific frequency bands for voice and rural coverage that differ from North American and some European device configurations. The critical bands are:
- Band 18 / Band 26 (au/Rakuten Mobile): Used extensively for rural and building-penetration coverage on the au/Rakuten network. Many smartphones sold outside Japan, particularly older US models, do not support Band 18.
- Band 19 (docomo): Docomo's rural coverage band. Similarly, not universally supported on non-Japanese handsets.
- Band 28 (700MHz, all carriers): Increasingly used for 5G and rural coverage across all Japanese carriers.
Before arriving in Japan, check your device's supported band list against the carrier you plan to use. Rakuten Mobile's network relies heavily on Band 18 for outdoor coverage and on roaming agreements with au for areas where Rakuten's own towers have gaps.
eSIM: The Fastest Activation Option
eSIM availability from Japanese carriers has expanded significantly. If your device supports eSIM (most smartphones released since 2019 do), you can activate a Japanese number within minutes of completing the online application, with no physical SIM card required.
Carriers offering eSIM in Japan (2026):
- Rakuten Mobile: eSIM activation available entirely through the app
- IIJmio: eSIM plans available, activation through the IIJmio management portal
- au/UQ Mobile: eSIM available on contract plans
- SoftBank: eSIM available
The practical advantage of eSIM for a new arrival is speed. If you have a compatible device, you can complete Rakuten Mobile's online application, receive eSIM activation, and have a working Japanese number the same day without visiting a physical store or waiting for a card to arrive by post.
Number Porting (MNP): Keeping Your Number When Switching Carriers
If you start on a prepaid SIM and later want to move to a contract plan while keeping the same number, Japan has a number portability system (MNP) that allows this.
The MNP process:
- Contact your current carrier to request an MNP reservation number (MNP予約番号). This can usually be done online or by phone.
- The reservation number is valid for 15 days.
- Apply to your new carrier, providing the MNP reservation number during signup.
- The number transfer is completed within 1-2 business days. There is typically a brief period of a few hours when the number is inactive during the transfer.
Most major carriers no longer charge a separate MNP transfer fee in the way they once did, though the exact process and any related administrative charges are worth checking before you switch.
Bottom Line
Get a Japanese phone number as early as possible after arrival — it unlocks banking, delivery, and a large share of the online services you will need. The fastest path for someone who has just landed is a voice-capable SIM or eSIM that can be activated quickly with residence-card verification. A practical low-cost path once you have a residence card and a working payment method is Rakuten Bank followed by Rakuten Mobile, especially if your device supports eSIM. Port your number via MNP once you have identified your long-term carrier preference — there is little reason to give up a number you have already tied to banks and services.