You just arrived in Japan.
You bought a data-only SIM at the airport, and the internet works.
“I’m all set now,” you think. Right? Yeah.
But a few days later, you get stuck.
”The internet works” and “I can live in Japan” are different things
A data-only SIM just connects you to the internet.
Life in Japan calls for plenty of things beyond an internet connection.
- Creating a LINE account
- Opening a bank account, or logging in to a bank app
- Registering for services that require a mobile phone to sign up
- Getting calls from delivery drivers, real estate agents, or your workplace
What many of these ask for is a phone number, plus an SMS (text message) sent to that number.
What is SMS verification?
When you register or log in, a numeric verification code is sent to your phone number.
You type it into the screen, and that confirms “yes, this is really your phone.”
In Japan, a lot of services use this method.
Here’s where the type of SIM becomes a problem.
Data-only SIMs and tourist eSIMs often have no phone number, or can’t receive SMS.
If you can’t receive SMS, the code never arrives, and your registration doesn’t go through.
The classic “stuck” pattern
This is how it usually goes.
- You buy a data-only SIM on arrival
- You try to register for LINE and the verification code doesn’t arrive
- You try to do bank paperwork and they ask for a Japanese mobile number
- Your workplace or real estate agent says “we’ll contact you by phone” and you have no number
Each one is small, but piled together, they bring your life to a halt.
What to get first
Here’s the conclusion. Get a SIM with a Japanese phone number that supports voice calls.
What you generally need for the contract is these three things.
- Residence Card (在留カード) (as proof of identity)
- A payment method (a credit card, or a debit card or bank transfer, etc.)
- A smartphone
With Rakuten Mobile, domestic calls through the Rakuten Link app are free, and you get both a phone number and SMS. For people without a credit card, we’ve put together a separate article.
Application requirements and procedures can change, so check the official page for the final word.
Summary
- A data-only SIM just connects you to the internet. Often no phone number or SMS
- In Japan, LINE, banks, and various registrations often require SMS verification
- Without a phone number, you get stuck in all sorts of places in daily life
- The shortcut is to first sign up for a voice-call SIM with a Japanese phone number
Don’t relax just because “the internet works.”
A phone number is your entry ticket to living in Japan.
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