Japan Prep Guide
How to Set Up an eSIM for Japan (iPhone and Android)
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Setting up a travel eSIM for Japan takes about ten minutes, and most of it can be done at home. This guide walks through each step on iPhone and Android, from checking your phone is compatible to fixing the most common "no internet" problem after landing.
Quick answer: 1) Check your phone supports eSIM and is carrier-unlocked. 2) Buy a Japan eSIM and install it on WiFi a day or two before you fly. 3) When you land, turn on the Japan eSIM, set it as your mobile data line and switch Data Roaming on for the eSIM (and off for your home SIM). 4) No connection? Toggle airplane mode, restart and check the APN. Never delete the eSIM while troubleshooting.
Step 1: Check your phone is compatible and unlocked
You need two things: a phone that supports eSIM, and a phone that isn't locked to your home carrier.
iPhone
- eSIM support: iPhone XS, XR and later support eSIM. US models from iPhone 14 onwards are eSIM-only.
- Unlock status: go to Settings > General > About and look at Carrier Lock. "No SIM restrictions" means your iPhone is unlocked. If you see anything else, contact your carrier, as only they can unlock it.
Android
- eSIM support: open Settings > Network & internet (or Connections) > SIMs / SIM manager and look for an option like "Add eSIM" or "Download a SIM". You can also dial *#06#: if an EID number appears, the phone supports eSIM (some phones support eSIM but don't show it, so check the manufacturer's specs if unsure).
- Unlock status: there's no universal menu on Android. Ask your carrier, check your account online, or try a friend's SIM from another network. Some phones sold in certain regions don't support eSIM at all (for example, many iPhone models sold in mainland China use two physical SIM slots instead), so double-check if your phone came from a different country.
Not sure? GigSky offers a free 100 MB trial plan in its app with no card needed. If it installs, your phone can take a travel eSIM.
Step 2: Buy and install the eSIM before you fly
Choose a plan (our Japan eSIM comparison and data calculator can help), then install it at home over WiFi, ideally one or two days before departure.
Why at home? Installing needs an internet connection, and airport WiFi or a dead home SIM on arrival makes it harder. On most plans, installing does not start the clock: Airalo says most of its packages start their validity when the eSIM connects to a supported network in the destination, and Saily says installing doesn't use data or start the plan. Some plans do start on installation, though, so read your plan's validity terms first.
Installing on iPhone
- Use the provider's app (the easiest option; many offer one-tap install) or scan the QR code via Settings > Cellular (Mobile Data) > Add eSIM.
- Give the new line a clear label, such as "Japan".
- When asked, keep your home number as the default for calls and iMessage/FaceTime if you want to keep receiving texts.
- For now, set mobile data to your home line, or turn the Japan line off, until you land.
Installing on Android
- Use the provider's app or go to Settings > Network & internet > SIMs > Add eSIM / Download a SIM and scan the QR code.
- Rename the eSIM "Japan" so it's easy to find.
- Leave it switched off until you arrive if your phone asks.
Some providers also show APN details on the installation screen. Screenshot them in case you need them later.
See Saily's Japan eSIM plans (opens in a new tab) See Airalo's Japan eSIM plans (opens in a new tab)
Step 3: Activate it when you land in Japan
- Turn off airplane mode once you're allowed to.
- Switch the Japan line on (iPhone: Settings > Cellular > tap the Japan line > Turn On This Line; Android: Settings > Network & internet > SIMs).
- Set the Japan eSIM as your mobile data line (iPhone: Settings > Cellular > Cellular Data).
- Turn Data Roaming on for the Japan eSIM. Travel eSIMs usually work as "roaming" connections, so without this they often won't connect.
- Turn Data Roaming off for your home SIM so you don't get charged by your home carrier. On iPhone, also make sure "Allow Cellular Data Switching" is off unless you want both lines used.
Wait a minute or two. You should see a Japanese network name (such as docomo, SoftBank or au/KDDI) and 4G/5G at the top of the screen.
Step 4: Troubleshooting
Find your symptom in the table, then see the detailed steps below.
| Symptom | Likely cause | Fix |
|---|---|---|
| "No Service" or "SOS only" | Japan line switched off, or Data Roaming off for it | Turn the line on, enable Data Roaming for the Japan eSIM, then toggle airplane mode for 30 seconds |
| Signal bars but no internet | Mobile data still set to your home SIM, or wrong APN | Set the Japan eSIM as the mobile data line; enter the provider's APN (common on Android) |
| Connected but very slow | Daily high-speed limit reached, or a congested network | Check usage in the provider's app; try manual network selection; top up or wait for the daily reset |
| QR code "cannot be added" or "invalid" | Phone is carrier-locked, or the code was already used | Check Carrier Lock / unlock status; contact the provider for a new profile rather than rescanning |
| Home carrier roaming texts or charges | Data Roaming still on for your home SIM | Turn Data Roaming off for the home line; on iPhone, turn off Allow Cellular Data Switching |
| Hotspot not working | Plan doesn't allow tethering, or hotspot APN missing | Check the plan's hotspot rules; on Android, add the hotspot APN type if the provider gives one |
No signal at all
- Toggle airplane mode on for about 30 seconds, then off.
- Restart the phone.
- Check the Japan line is switched on and Data Roaming is on for it.
- Try selecting a network manually (Settings > Cellular > Japan line > Network Selection on iPhone, or Mobile network > Network operators on Android), choosing a network your plan supports.
Signal bars but no internet
This usually means data is still going through your home SIM. Re-check which line is set for mobile data. If that's correct, check the APN: most eSIMs set it automatically, but some Android phones need it entered by hand (Settings > Mobile network > Access Point Names). Use the exact APN your provider gives you, and remove old APNs from previous trips if they conflict.
Still stuck?
Contact the provider through its app's live chat. Hotel or airport WiFi will get you online to do this.
Important: don't delete or "remove" the eSIM while troubleshooting. Many travel eSIM QR codes can only be used once, so a deleted profile may not be reinstallable without the provider's help.
Keeping your home number for SMS codes
Your bank or other services may text you one-time passcodes while you're away. With a dual-SIM phone you can keep your home SIM switched on for calls and SMS while the Japan eSIM handles data:
- Leave your home line on but with data roaming off.
- You can usually receive texts this way, but your home carrier may charge for incoming calls or texts abroad, so check its roaming rates.
- iMessage, FaceTime and WhatsApp keep working with your usual number over the Japan eSIM's data.
If you don't need your home number at all, you can switch that line off completely and turn it back on when you return.
FAQ
Can I install the eSIM on the plane or at the airport?
You can, as long as you have WiFi, but it's less stressful at home. Many airports in Japan have free WiFi if you forget.
Will I get a Japanese phone number?
Not with most travel eSIMs. They're data-only, so use apps like WhatsApp or LINE for calls. A Japanese number generally requires a voice SIM from a local provider with ID checks.
Can I use my eSIM as a hotspot?
Most travel eSIMs allow it. Turn on Personal Hotspot (iPhone) or Hotspot & tethering (Android) and keep an eye on your data, since laptops use a lot.
Should I choose an eSIM or pocket WiFi?
eSIMs are cheaper and lighter for solo travellers; pocket WiFi can make sense for groups or older phones. See eSIM vs pocket WiFi for Japan.
Bottom line
Check your phone is unlocked, install the eSIM at home, and when you land switch on the Japan line, make it your data line and enable roaming for it. That covers most problems before they happen. If you want to test compatibility first, try GigSky's free trial (opens in a new tab) before buying a full plan.
Related guides
- Japan in winter: 7 things to book in advance
- eSIM vs Pocket WiFi vs SIM card for Japan
- Narita & Haneda Airport to Tokyo
- How much mobile data do you need in Japan?
- Best Japanese snack box gift for the holidays
- Gifts for anime fans shipped from Japan
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