If you've been living in Japan for a while, you've probably built up a Japanese phone number that your bank, workplace, and friends all know. The good news is that mobile number portability in Japan for foreigners is absolutely possible — you don't have to give up your number just because you're switching SIM providers. This guide walks you through exactly how it works, what you need, and what to watch out for.
What Is MNP (Mobile Number Portability)?
MNP stands for Mobile Number Portability — in Japanese, it's called 番号ポータビリティ (bangou portability). It's a system that lets you take your existing phone number with you when you move from one carrier to another. So if you switch from docomo to an MVNO, or from SoftBank to a more foreigner-friendly provider, your number stays the same.
This matters a lot in Japan, because your phone number is often tied to your bank account two-factor authentication, your MyNumber card verification, and your employer's records. Changing it can cause real headaches.
Who Can Use MNP in Japan?
Any registered subscriber — including foreign residents — can use MNP as long as:
- You have a valid residence card (在留カード, Zairyu Card)
- Your current contract is in your own name
- You have a Japanese address registered with your local municipality
- You are not within a minimum contract period that blocks transfers (check your current contract terms)
If your contract is in someone else's name (for example, a previous employer or landlord), you will need to have it transferred to your name first before you can port the number out.
Step-by-Step: How to Transfer Your Number in Japan
Step 1 — Get Your MNP Reservation Number (MNP予約番号)
Contact your current carrier and request an MNP reservation number. You can usually do this:
- Online through your carrier's My Page account
- By calling the carrier's customer service line
- In person at a carrier store (bring your residence card and the SIM/device)
The reservation number is valid for 15 days, so don't request it until you're ready to sign up with your new provider. Note: some carriers charge a small MNP transfer fee — confirm the current amount directly with your carrier, as fees and rules change.
Step 2 — Choose Your New Provider
This is the perfect moment to find a plan that actually suits you. When comparing providers, look at:
- Monthly cost and data allowance
- Whether they require a Japanese credit card or Japanese bank account
- Contract length and cancellation conditions
- Language support (English, Chinese, etc.)
- Voice calls included, or data only
The major carriers — docomo, au, and SoftBank — often require a Japanese credit card and can be difficult for newcomers to sign up with directly. If you're a foreign resident, consider foreigner-friendly MVNOs:
| Provider | Japanese Credit Card Required? | Language Support | Notes |
|---|---|---|---|
| GTN Mobile | No | Multilingual | Accepts residence card; flexible payment options; popular with foreign residents |
| Mobal | No | English | No Japanese bank account needed; designed for foreigners |
| IIJmio / OCN Mobile | Generally yes | Japanese mainly | Good value plans; may be trickier for new arrivals |
Plans and requirements change frequently. Always confirm the latest details on each provider's official website before signing up.
Step 3 — Apply to Your New Provider with the MNP Number
When you apply to your new provider, you'll enter your MNP reservation number as part of the sign-up process. Have these ready:
- Your MNP reservation number (and its expiry date)
- Your residence card
- Your registered Japanese address
- Your payment method (credit card, debit card, or bank account depending on the provider)
For online applications, the process is usually straightforward and guided in English if you choose a foreigner-friendly MVNO.
Step 4 — Wait for Activation
Once your application is approved and your new SIM arrives (or your eSIM is issued), you'll go through a brief activation step. During this time — usually just a few minutes to a couple of hours — your old SIM will stop working and the new one will take over with your existing number.
Plan this switch for a time when you don't urgently need your phone, just to be safe.
Common Questions About MNP for Foreign Residents
Can I use MNP if I'm on a prepaid SIM?
It depends on the prepaid SIM provider. Some prepaid plans in Japan do support MNP out, but not all do. Check directly with your current provider before assuming you can port the number.
What if my Japanese is limited?
Calling your current carrier to request an MNP number can be the trickiest part if you're not confident in Japanese. Some carriers have English-language support lines — check your carrier's website. Alternatively, visiting a store in person and bringing a translation app can help. Foreigner-friendly MVNOs like GTN Mobile offer multilingual support for the sign-up side of things.
Is there a cost to transfer?
Rules around MNP fees have been updated in recent years in Japan, with the government pushing carriers to reduce or eliminate transfer fees. That said, some carriers may still apply conditions or administrative charges. Check your current contract and carrier's latest policy to know exactly what applies to you.
What happens to my old contract?
Completing the MNP transfer automatically cancels your old contract. However, be aware of any early termination fees if you're within a minimum contract period. Always check before you start the process.
Summary: Keeping Your Number Is Easier Than You Think
Mobile number portability in Japan for foreigners is a well-established process — you don't need to be a citizen or have perfect Japanese to use it. The key steps are simple: get your MNP reservation number from your current carrier, choose a new provider that works for your situation (especially if you need multilingual support or don't have a Japanese credit card), and apply with your residence card and the reservation number in hand.
If you've been putting off switching because you didn't want to lose your number, now you know you don't have to. Take your time comparing plans, pick a provider that fits your life in Japan, and make the move with confidence. Your number — and everything connected to it — comes with you.