It’s night. You’ve finished packing, and your passport is waiting by the front door. All that’s left is to go to bed — but before you do, you pick up your phone.
You connect to your home Wi-Fi and install the travel eSIM you bought. That’s it for tomorrow’s prep.
The next day, you land at an airport in Japan and turn off Airplane Mode. Switch the line you use for data to your travel eSIM, and your map opens and shows the way to where you’re staying.
This article is about those 2 moments: installing it the night before and switching over at the airport.
Even if you install it the night before, with Airalo, in most cases your days are counted from when you arrive in Japan and connect to a supported network. With other providers and plans, the count may start from the moment you install, so check the plan description before you buy.
Three things to do by the night before
- Check that your phone can use eSIM
- Choose a plan and buy it
- Install it on your home Wi-Fi
After that, you just switch over at the airport.
1 Can your phone use it?
If you have an iPhone, eSIM works on the iPhone XS, XS Max, XR and later models.
The other thing to check is the SIM lock. If “Settings” > “General” > “About” shows “No SIM restrictions” next to “Carrier Lock,” you can install a travel eSIM. If your phone is locked, a travel eSIM won’t work.
There’s one exception. Some iPhones bought in China mainland don’t support eSIM. In Hong Kong and Macao, some models take 2 physical SIM cards. If you bought your iPhone in one of these places, check your model’s specs in Settings beforehand.
On Android, it depends on the phone. Google Pixel phones from the 3a onward can use eSIM. On Samsung phones, even with the same model name, eSIM may not work depending on the country where you bought the phone. Don’t go by the model name alone — check with the manufacturer.
Even if your phone can’t use eSIM, you still have options. “SIM cards” and “pocket Wi-Fi” each have their own article.
2 Choosing a plan — days and data
Travel eSIMs come as combinations of days and data. From 3 to 30 days, from a few GB to “unlimited” — what’s on offer varies from provider to provider.
There’s no set rule for how much data you need. A trip that’s mostly maps and train transfers is very different from one where you watch a lot of videos. If you run short, some providers let you top up the same eSIM later.
“The day you install” and “the day the count starts” are two different things
If you install it the night before, won’t your days start running down from that day? That may be the thing you’re most worried about.
With Airalo, in most cases the count starts from when you connect to a supported network in Japan. With other providers and plans, check the plan description before you buy. If your plan counts from the moment you install, install it just before you arrive.
One more thing. Some providers explain that the data amount is what you can use over the whole period, not per day.
Read the plan description for “unlimited”
Even plans sold as “unlimited” may have limits on how much you can use. For example, on Airalo’s unlimited plans for Japan, the speed drops to 1Mbps once you go over 3GB in a day. Airalo explains that this is still enough for messages and maps, but not suited to watching a lot of videos.
What “unlimited” really means is written in the plan description. Read that part before you buy.
Tethering and phone numbers
Whether you can use tethering, or personal hotspot, depends on your phone and your line. If you want to share data with a tablet or computer, check the plan description before you buy.
The eSIMs from the 2 providers in the next section are both data-only. They don’t come with a phone number. On iPhone, even if you use only your travel eSIM, FaceTime and iMessage may continue to work with your home number. Check the settings and charges with your home carrier. For when you need a Japanese phone number, see the article “When You Need a Japanese Phone Number.”
3 Example providers — Airalo and IIJ
Lots of companies sell travel eSIMs. Here are 2 examples that work in different ways.
- Airalo — You buy it online and can install it before you leave. It uses the SoftBank and KDDI networks in Japan. Plans run from 3 to 30 days, and there are “unlimited” plans too.
- IIJ (Japan Travel SIM) — A Japanese company. Data only. The data-volume plans are valid for 30 days, and there is also an “Unlimited” plan with a choice of validity period (this one comes as a SIM card only). It works wherever docomo’s network reaches. You can buy it at convenience stores such as Lawson.
4 The night before — install it on your home Wi-Fi
After you buy, the provider sends you instructions for installing it. Sometimes it’s a QR code, and sometimes you install it through the provider’s app.
- QR code — Scan it with your iPhone camera, tap the notification that appears, and follow the steps on the screen. If you’re asked for a confirmation code, enter the number the provider sent you
- Only have one phone — With iOS 17.4 or later, touch and hold the QR code you received by email or in your browser, and an Add eSIM button appears. You don’t need to show the QR code on a second device’s screen
- Android — Go to Settings, add an eSIM, and scan the QR code. Menu names differ from phone to phone
On iPhone, you may be asked partway through whether you’ll use this eSIM at home or while traveling. Choose the traveling option.
Until it finishes installing, stay connected to Wi-Fi and don’t stop partway.
Even once it’s installed, it won’t connect tonight. It usually won’t work until you reach Japan. Even so, you’re all set.
Once it’s installed, don’t delete it — just leave it there
Don’t delete the eSIM you installed. Once you delete a travel eSIM, you usually can’t install it again. You may have to buy a new one.
As long as you don’t delete it by accident, nothing will go wrong. While you’re not using it, turning it off instead of deleting it is enough. Just note that with some providers, your days keep counting even when it’s off.
If you think you may have bought the wrong one, the quickest way is to contact the provider before you install it.
5 At the airport — switch over
When you get off the plane, turn off Airplane Mode.
On iPhones with iOS 26 or later, if you’ve installed a travel eSIM, a notification may appear when you arrive asking whether to turn on your travel eSIM. There are 2 choices: “Travel eSIM Only” and “Travel eSIM and Current eSIM.”
- Travel eSIM Only — You use the travel eSIM for data and don’t use your home carrier’s line. If you want to avoid roaming fees on your home carrier’s line, choose this one. FaceTime and iMessage may still work with your home number (check the settings and charges with your home carrier)
- Travel eSIM and Current eSIM — You use the travel eSIM for data, but Apple says you may still be charged roaming fees on your home carrier’s line. If you keep both, turn data roaming off on your home carrier’s line
Next, you’ll also be asked whether to turn on “Low Data Mode,” which saves data. If you’re worried about how much data you’ll use, turn it on.
If no notification appears, go to “Settings” > “Cellular” > “Cellular Data” (called “Mobile Data” in some regions) and choose your travel eSIM.
Turn data roaming on for your travel eSIM, as your provider instructs, and off for your home carrier’s line.
On Android, choose your travel eSIM as the SIM for data. On Pixel, for example, only 1 SIM can be used for data at a time. Menu names differ from phone to phone.
When you can’t connect
If your screen shows “No Service” or “SOS only,” try these first.
- Check that data roaming is on for your travel eSIM
- In “Settings” > “General” > “Date & Time,” check that Set Automatically is on (the clock may be wrong when you arrive)
- Turn on Airplane Mode for about 30 seconds, then turn it off
- Restart your phone. Turn your travel eSIM off, then on again
If it still won’t connect, contact the provider you bought it from before you delete the eSIM. For more, see the article “When Your Phone Won’t Connect in Japan.”
During your trip, and after you get home
You can see how much data you’ve used in “Settings” > “Cellular.” When you use it all up, your data stops or slows down. If that happens, top up.
When you get home, in some countries or regions, iPhones with iOS 26 or later automatically turn off your travel eSIM and switch you back to your home carrier’s line. If that hasn’t happened, turn on your home carrier’s line and turn off the travel eSIM.
If you keep the eSIM instead of deleting it, some providers let you top up the same eSIM the next time you come to Japan.
A quick step the night before, just before bed. When you arrive, just switch over. By the time you reach the airport arrivals lobby, your map is already open.
