Soon after you register your address in Karuizawa, you will hear about My Number (マイナンバー) — Japan's individual ID number system. Every resident, foreign or Japanese, gets one, and the physical My Number Card (マイナンバーカード) is becoming the standard way to prove your identity, collect official documents, and even show your health insurance. This guide explains the difference between the number and the card, what the card does, and how to apply in Karuizawa. If you have not registered your address yet, do that first — see How to Register Your Address in Japan (転入届).
TL;DR
- My Number (マイナンバー) is a 12-digit number assigned to every resident automatically after address registration — you do nothing to receive it.
- The My Number Card (マイナンバーカード) is an optional photo-ID card you apply for separately.
- The card works as government photo ID, lets you print certificates like your 住民票 at convenience stores, and can act as your health insurance card (マイナ保険証).
- Apply online, by mail, or at a photo booth, then collect it in person at Karuizawa Town Hall about a month later.
What is My Number (マイナンバー)?
My Number is a 12-digit individual number (個人番号) assigned to everyone listed on Japan's resident register, including foreign residents. It is used for tax, social security, and disaster-response procedures. Your employer, bank, and the town hall will all ask for it at various points, so keep it somewhere safe and private.
Do foreigners get a My Number?
Yes — automatically. Once you complete your moving-in notification (転入届) at the town hall, a My Number is assigned to you, and a notification letter (個人番号通知書) is mailed to your registered address. You do not apply for the number itself; you only apply if you want the physical card.
My Number vs. the My Number Card
These are two different things:
- My Number (the number) — the 12-digit number itself. Everyone has one. Mostly paperwork.
- My Number Card (the card) — an optional IC card with your photo, name, address, and number. It is official photo ID and enables online and in-store services.
You can live in Japan with just the number, but the card removes a lot of friction.
How do I apply for a My Number Card?
There are a few routes, and you finish by collecting the card in person:
- Apply using the issuance application ID printed on your notification — online via smartphone, by mail, or at a participating photo booth. You submit a photo that meets the spec.
- Wait about a month while the card is produced. A collection notice is mailed to you.
- Collect in person at Karuizawa Town Hall, bringing the collection notice and your residence card (在留カード). You set a PIN/password during pickup.
What can I use the My Number Card for?
- Government photo ID — a single card accepted across many procedures.
- Convenience-store certificates — print your residence certificate (住民票), seal-registration certificate, and certain tax documents at a konbini multi-copier, often cheaper and outside town-hall hours.
- Health insurance (マイナ保険証) — register the card as your insurance card (see below).
- Online tax filing (e-Tax) and various online government services.
Using the card as a health insurance card (マイナ保険証)
The My Number Card can be linked to your health insurance and used at clinics and hospitals as a マイナ保険証. Japan is phasing out the separate paper health insurance card, so registering your My Number Card is increasingly the standard way to show coverage. If you are enrolling in National Health Insurance, ask at the town hall how to link it.
How long is the card valid?
For most foreign residents, the card's validity is tied to the expiry of your residence card (period of stay). When you renew your residence status, update the My Number Card as well. Separately, the electronic certificates on the card (used for online login and e-Tax) expire every five years and need renewing.
Do I actually need one?
The card is optional, but in practice it saves repeated trips to the town hall, gives you a clean photo ID, and is becoming essential for health insurance and online services. For most residents settling in Karuizawa, it is worth applying for early. You will also be asked for your My Number when you open a bank account and start work.
How ERISA helps
ERISA (有限会社えり紗) explains which steps actually apply to your situation, helps you complete the My Number Card application (including the photo and the online form), and accompanies you to Karuizawa Town Hall to collect the card and set your PINs — interpreting throughout so nothing is missed. We can also link the related procedures, like residence registration and health insurance, into a single visit.
Settling into Karuizawa and not sure where to start? Get in touch.