Getting connected
Japan eSIM vs pocket WiFi: what actually goes wrong
Solo, with an unlocked phone: buy an eSIM. Two or more people, or a laptop you need online: rent pocket WiFi. Phone locked to your home carrier: physical SIM, and only that. That is the whole decision. It takes about ninety seconds.
What takes longer — and what nobody warns you about — is the part after you buy. Somewhere between the jet bridge and the ticket machine, a meaningful number of people discover their data does not work, and every one of them assumes they bought a bad product. Usually they didn’t. They missed a setting.
Almost every comparison you will read on this subject is published by a company that sells one of these three things. They are not lying to you, but they are all steering toward the same conclusion, and none of them will tell you when not to buy. This page does.
The ninety-second version
| Your situation | Get this | Realistic cost |
|---|---|---|
| Travelling alone, recent unlocked phone | eSIM | Around $4 for 1GB; $10–17 covers most one to two week trips |
| Two or more people sharing | Pocket WiFi | ¥400–1,200 per day before add-ons, split between you |
| Working from a laptop, video calls | Pocket WiFi | Same, and take the spare battery |
| Phone locked to your home carrier | Physical SIM | Roughly ¥2,000–6,000 for 7–30 days, more at airport counters |
| Phone has no eSIM hardware | Physical SIM or pocket WiFi | As above |
Those are ranges rather than prices, deliberately. This market moves, discount codes are everywhere, and the same provider will show you three different numbers depending on which blog sent you. Treat the ranges as a sanity check: if a quote sits well outside them, find out why before paying.
For one person with a modern phone, the maths is not close. An eSIM costs less than a couple of coffees, arrives by email, and needs no counter, no deposit, no return. Pocket WiFi only wins when the device is doing work a single phone cannot do: feeding several people, or keeping a laptop online all day.
Two pricing traps
The advertised daily rate is not what you pay
Pocket WiFi is marketed on a headline daily figure — you will see “from ¥440 a day” and similar. That number is real, and it is also not the number on your card. What gets added at checkout:
- A security deposit. Commonly around ¥10,000, refundable, but held against your card for the trip.
- A setup or handling fee. Some providers charge a few thousand yen once, which wrecks the daily maths on a short trip.
- Shipping or delivery. Free above a certain rental length with some providers, several hundred yen otherwise.
- The power bank. Sometimes included, sometimes an extra charge per day. You will want it either way.
- Damage insurance. Optional, until you consider that losing the device can cost tens of thousands of yen.
The providers with the most aggressive headline rates tend to be the ones with the most added at the end. The only comparison that means anything is the final checkout total for your exact dates, with the power bank included. Do that for two providers and the ranking often flips.
Buying at an airport counter on arrival costs more than reserving the same device online beforehand, and you queue for the privilege.
“Unlimited” almost never means unlimited
Nearly every unlimited plan in Japan, on both pocket WiFi and eSIM, runs a fair usage policy underneath. You get a daily high-speed allowance, and after that the connection is throttled until the day rolls over.
One widely sold eSIM marketed as unlimited gives 3GB per day at full speed and then drops to around 1Mbps. That is still usable for maps and messaging, and useless for anything else. Throttled is not the same as cut off, but it is also not what the word on the product page implies.
If you genuinely need heavy data, a large fixed-data plan is often better value than an unlimited one, and it will not slow down on you at 4pm.
Worth knowing on price: at least one major eSIM provider raised its Japan unlimited pricing sharply in early 2026, roughly doubling some durations. Reviews and comparison tables written before that are still circulating. Check the live price, not the article that recommended it.
The five things that actually go wrong
In rough order of how often they catch people out.
1. Data roaming is switched off
This is the big one, and it is genuinely counterintuitive. A Japanese eSIM is a local plan — you are not roaming in any normal sense — but your phone still classifies it as a roaming connection and will refuse to use it unless data roaming is enabled for that specific line.
People land, see “No Service,” and conclude the eSIM is broken. It isn’t. On iPhone the toggle sits under Settings → Cellular → Cellular Data Options. On Android it is usually under Connections → Mobile Networks → Data Roaming. Either way, the important part is that it must be on for the Japanese line, not just globally.
2. The phone is locked to your home carrier
A carrier-locked phone cannot use any foreign SIM or eSIM, and no amount of troubleshooting at the airport will change that. Check before you buy anything.
On iPhone: Settings → General → About, and scroll to Carrier Lock. You want it to say there are no SIM restrictions. Anything else means locked. On Android the path varies by manufacturer, and the fastest answer is often to ask your carrier directly.
If it is locked, ask your carrier to unlock it. This is usually free once the device is paid off, and often takes a few business days — which is why this is a two-weeks-before-you-fly job, not a night-before one.
3. The phone has no eSIM hardware at all
Not every phone supports eSIM, and here is the part that surprises people: the same model can differ by region. Certain variants sold in mainland China, Hong Kong and Macau ship without eSIM support even when the identical model number elsewhere has it.
The reliable test is whether your phone has an EID number, or whether the settings offer an “Add eSIM” option. If neither is there, stop reading the eSIM sections — you need a physical SIM or a pocket WiFi, and that is fine.
4. Installed is not the same as activated
On a dual-SIM phone your home SIM and the Japanese eSIM coexist peacefully, and by default the phone usually keeps using your home line for data. The Japanese plan sits there, installed, correct, and completely idle, while your home carrier quietly charges you international roaming rates.
After installing, go into the cellular settings and explicitly set the Japanese eSIM as the line used for mobile data. While you are there, turn your home line’s data off entirely. That single step prevents the most expensive mistake on this page.
5. You waited until you landed to install it
Installing an eSIM requires an internet connection, because the profile has to be downloaded. If you plan to do that after landing, you need working internet to get working internet.
Airport WiFi will usually rescue you, but not always quickly, and not while you are queuing. Install the profile at home, on your own WiFi, days before you fly.
One caution here, because it varies and it matters: check when your plan’s clock starts. Some plans begin counting only when the eSIM first connects to a Japanese network, which means installing early is free. Others start on a fixed date or from the moment of purchase, which means installing early quietly burns days you paid for. The provider states this at checkout. Read it before you buy, not after.
What the sellers leave out
Two things that are consistently reported by travellers and consistently absent from vendor pages. Neither is a measured claim — treat them as what to expect, not as a guarantee.
Signal inside the terminal is often the worst signal of your trip. Arrival halls are large, heavily built, and full of people all connecting at once. Travellers regularly report weak, slow data inside the building that improves noticeably once they are outside or on the platform. If your first three minutes are bad, walk twenty metres before you conclude anything.
Underground is slower than street level. Japanese subway coverage is genuinely good — you can use data on most trains — but speeds drop below ground compared with what you get on the surface. Plan around it: load your route while you are still upstairs.
Who should not buy an eSIM
Being direct about this, because the pages that rank above this one will not be.
- Anyone whose phone is locked or lacks eSIM hardware. No workaround exists. Buy a physical SIM.
- Groups of three or more. Buying separate eSIMs for everyone is usually more expensive than one shared pocket WiFi, and everyone is walking around together anyway.
- Anyone who has to work properly from a laptop. Tethering from a phone all day works until your phone battery decides otherwise, which is generally mid-afternoon on the day it matters most.
- Anyone genuinely uncomfortable changing phone settings. There is no shame in this. Pocket WiFi is a box you switch on, and if the alternative is standing in an arrivals hall fighting a settings menu, take the box.
And one note in the other direction: if you do rent pocket WiFi, take the spare battery. Devices vary a lot — some run around nine hours, the better ones closer to twenty — and nine hours sounds like plenty until you use maps continuously. A router that dies at 3pm in an unfamiliar city is a solved problem — solve it at the counter.
Ten minutes, before you fly
Do this on your own WiFi, at home, at least a few days out.
- Check the phone is unlocked. If not, request the unlock now — it takes days, not minutes.
- Check the phone has eSIM support at all.
- Buy the plan and install the profile. Do not wait until arrival.
- Label the line clearly, so you can find it in a hurry.
- Set the Japanese eSIM as your mobile data line.
- Turn data roaming on for that line.
- Turn your home line’s data off.
- Screenshot your booking confirmation and the activation code.
- Download offline maps for the cities you are visiting.
- Complete your pre-arrival immigration registration and screenshot the QR code.
Steps 8 through 10 exist for the same reason: everything on this list assumes a working phone, and a screenshot works whether or not the network does.
The short answer
Alone with an unlocked modern phone, buy an eSIM, install it at home, set it as your data line, and turn roaming on for it. Two or more of you, or a laptop in the bag, rent pocket WiFi and take the battery. Locked phone, buy a physical SIM and stop reading comparison articles.
If it does not work when you land, it is almost certainly item 1 or item 4 above, and it is almost certainly fixable in under a minute — once you are twenty metres from the arrivals hall.