Updated: 2026-08-10 10:39:21
You have landed in Japan, opened your phone, and the eSIM you bought is showing nothing. No signal, no data, no maps — and the train you need to catch leaves in twelve minutes. It is a genuinely stressful moment, and it happens to more travelers than you would think.
The good news: almost every "eSIM not working in Japan" case comes down to a small number of settings, and most are fixed in under five minutes. The eight checks below are ordered by how often they turn up in our actual support inbox, not by textbook logic — so start at the top and work down.
And if you get to the end and are still offline, the last section explains exactly how to reach our support team when you have no mobile data at all. That part is the one most guides leave out, and it is the reason a lot of travelers stay stuck longer than they need to.
The three fixes that solve most cases
What this guide covers
This is the single most common cause. On a dual-SIM phone, installing an eSIM does not automatically make it your data connection. Your home SIM usually stays selected, and since it has no usable service in Japan, the phone looks completely dead even though the eSIM is sitting there fully working.
Also worth doing: turn mobile data off entirely for your home SIM. Otherwise the phone may quietly hop back to it when the signal fluctuates — which both breaks your connection and can trigger international roaming charges on your home bill.
Separate from the data-source setting above, each SIM line has its own on/off switch. A newly installed eSIM is sometimes left in the off state, particularly if you installed it before departure and skipped through the setup prompts.
On iPhone, go to Settings → Cellular, tap the eSIM plan name, and make sure Turn On This Line is enabled. On Android, open the SIM manager and confirm the eSIM is toggled on rather than greyed out.
This trips up a lot of people, because the correct answer is the opposite depending on which type you have:
| Type of eSIM | Data roaming | Why |
|---|---|---|
| Local Japan eSIM (including CDJapan Rental's eSIM) |
Not required | It connects directly to the docomo network as a domestic line, so there is nothing to roam onto |
| Roaming / international eSIM (regional or global products) |
Must be ON | It registers as a foreign SIM visiting a Japanese network, so roaming is the connection method itself |
If you are not sure which you bought, check the product page: if the plan lists a specific Japanese carrier such as docomo and covers Japan only, it is a local eSIM. If it covers multiple countries, it is a roaming product. We cover this distinction in more depth in our guide to local docomo connections versus roaming eSIMs.
Regardless of type: keep data roaming switched off on your home SIM. This is the setting that produces surprise bills after a trip.
Unglamorous, but it resolves a real share of cases. When you land, your phone has to release the cached network state from your departure country and register onto a Japanese tower. That handover does not always happen cleanly, especially if the phone was in airplane mode for a long flight.
A full restart is more thorough than the airplane-mode toggle, because it reloads the carrier profile that was installed with your eSIM. If you have just finished changing settings in Checks 01 and 02, restart before concluding they did not work.
Installing an eSIM, activating it, and the plan's validity period beginning are three different events — and different providers draw the lines in different places. If your plan has not started, or has already expired, the profile will sit on your phone looking perfectly healthy while delivering no data.
Other providers draw these lines differently, and some start the countdown from the purchase date rather than first use. If you bought elsewhere, check their terms rather than assuming ours apply — it is a common reason a plan appears to have expired before the trip even started.
Fixed-data plans throttle once the included allowance is gone. Unlimited plans work differently: with CDJapan Rental you get 3GB per day at full speed, after which the speed drops to 200 kbps until the daily allowance resets — there is no total cap and no disconnection, so the connection stays alive throughout. If pages are loading but painfully slowly, that is throttling rather than a fault, and our guide to slow Japan eSIM speeds goes into what to expect.
You can check your remaining data and validity any time from My Page.
The APN (Access Point Name) tells your phone how to reach the mobile data network. It is worth being precise here, because a lot of advice online tells iPhone users to go and edit their APN — which is not something an iPhone actually allows.
On iPhone the APN is carrier-locked and supplied by a configuration profile, so there is no field for you to type into. If the APN is the problem, the fix is to reinstall the configuration profile that came with your eSIM, not to hunt for a settings screen that will not appear. Your provider can reissue it.
Important distinction: reinstalling an APN profile is not the same as deleting and reinstalling the eSIM. Do not delete your eSIM to solve an APN problem — contact support first.
Some Android handsets do not apply the correct APN automatically after an eSIM install. Go to Settings → Connections → Mobile networks, select the eSIM, open Access Point Names, and confirm an entry for your provider exists and is selected. If it is missing, add it using the values from your setup guide, save, and restart.
With CDJapan Rental's eSIM, APN setup is not normally required on either platform — the settings apply automatically. If you are being asked to configure an APN by hand for a plan of ours, that itself is a signal something went wrong during install, and it is worth contacting us rather than working around it.
A carrier lock is a restriction your home network places on the handset, preventing it from connecting through any other operator. A locked phone will install a Japan eSIM without complaint and then refuse to connect to it — which is exactly the confusing symptom that brings people to this page.
On iPhone: Settings → General → About, then scroll to Carrier Lock. If it reads "No SIM restrictions", you are unlocked and this is not your problem.
On Android: the path varies by manufacturer, but Settings → About phone → SIM card status is the usual place. If it is unclear, your home carrier can confirm directly.
If your phone is locked, the only fix is to request an unlock from your home carrier. Most will do this free once the device is paid off, though it typically takes one to three business days — which is not much help mid-trip. If you are stuck in Japan with a locked handset, a pocket WiFi rental is the realistic workaround, since it does not touch your phone's SIM at all.
Most travelers have already confirmed this before buying, but regional variants catch people out — two phones with identical model names can differ if they were sold in different markets.
| Brand | eSIM-capable models | Watch out for |
|---|---|---|
| Apple iPhone | iPhone XR / XS and everything newer | Mainland China variants have no eSIM; some Hong Kong and Macau variants are also excluded |
| Samsung Galaxy | S20 series onward, plus Fold and Flip lines | Chinese-market models generally lack eSIM support |
| Google Pixel | Pixel 3 and newer | Broadly the most reliable for eSIM setup |
| Other Android | Selected OPPO, Xiaomi and Sony flagships | Check the official spec sheet for "eSIM" explicitly, not just "Dual SIM" |
The quickest universal test: open your dialer and enter *#06#. If an EID number appears alongside the IMEI, your phone has an eSIM chip. Alternatively, on iPhone look for an "Add eSIM" option under Settings → Cellular.
If everything above checks out and you still see "No Service", the phone may not be latching onto a tower. Two things to try.
Go to Settings → Cellular → Network Selection (iPhone) or Settings → Connections → Mobile networks → Network operators (Android), turn off Automatic, and let the phone scan. Then pick the operator your eSIM uses — NTT DOCOMO for CDJapan Rental plans. Once it connects, you can switch back to Automatic.
Japanese carriers use 4G bands 1, 3, 19 and 26, and 5G bands n77, n78 and n79. International model phones almost always cover these; phones bought for a single domestic market sometimes do not. If you are getting a weak, patchy connection rather than none at all, band coverage is a plausible cause.
On 5G with CDJapan Rental: eSIMs activated on or after 1 July 2026 support the docomo 5G network. eSIMs activated before that date remain on 4G LTE and do not upgrade automatically. Actual 5G availability follows docomo's own 5G footprint, so rural areas and some mountainous regions still run on 4G LTE.
Also worth ruling out the mundane: underground stations, basement floors of department stores, and long tunnel sections on the Shinkansen all produce dead zones that have nothing to do with your eSIM.
Still shopping around, or need a replacement plan fast?
CDJapan Rental eSIMs run on the docomo network with instant QR code delivery, so you can be online within minutes of purchase. See all Japan eSIM plans.
Most troubleshooting guides end at "contact your provider" and leave you with an obvious problem: you have no internet, so how exactly are you supposed to contact anyone? Here is the practical version.
Before you write: Steps 1 and 2 below apply to any Japan eSIM. Step 3 is for travelers who bought a CDJapan Rental eSIM. If you bought your eSIM from another provider or from a reseller, please contact them directly — we have no access to orders we did not issue, so we cannot look up your plan, check its activation status, or reissue a QR code for it. Your provider's contact details are in your purchase confirmation email.
You do not need mobile data to send an email — any WiFi will do. Japan has less free public WiFi than it used to, though, so it is worth knowing which options actually still work:
If you are somewhere with none of the above, a hotel lobby or a chain cafe is almost always the fastest thing to walk to.
Once you are on WiFi, you can also re-check your QR code and plan status through your provider's account page — for CDJapan Rental customers that is My Page. This resolves a fair number of cases on its own.
Whoever you are writing to, sending these up front usually turns a multi-day email chain into a single reply:
If your eSIM came from us, email rental@cdjapan.co.jp or use our contact form. Both reach the same team and both are handled in English.
If you bought elsewhere, the four items above will still serve you well — just send them to the provider named on your receipt rather than to us.
We are a Japanese company operating from Japan, on the same docomo network your eSIM is using. That matters more than it sounds: when a traveler tells us they have no signal at a specific place, we can usually tell straight away whether that is a settings issue or genuinely a weak-coverage pocket, because we know the network. Resellers working from another country generally have to escalate the same question upstream and wait.
Replies go out during Japanese business hours, so if you are writing late at night local time, expect the answer the following morning. If your eSIM turns out to be faulty on our side rather than a settings issue, we reissue it — you are not left buying a second plan to cover our mistake.
One thing to avoid while you wait: do not delete the eSIM profile from your phone in frustration. It is rarely the fix, and it removes the very thing support needs to look at. With CDJapan Rental you can reinstall on the same device if you do delete it — your remaining data and validity stay intact — but the profile cannot be moved to a different phone, so a deletion made in the wrong moment can cost you time you do not have.
Work through Checks 01, 02 and 03 first, since a data-source or line-toggle problem produces exactly this symptom. If those are clean, the likely causes are a carrier lock (Check 06) or the phone failing to register on a tower, which manual network selection (Check 08) often solves.
No. CDJapan Rental's travel eSIM is a data-only plan, so voice calls and SMS are not supported. This surprises some travelers who assume a blank call screen means a fault. Data apps such as WhatsApp, LINE and FaceTime work normally over the connection.
With CDJapan Rental you can reinstall it on the same device, and your remaining data and validity period are unaffected. What is not possible is moving the profile to a different phone — an eSIM is bound to the device it was installed on. If you have already switched handsets, contact support before doing anything else.
Yes. Personal hotspot works by default on CDJapan Rental eSIMs, with no extra configuration needed. If hotspot specifically fails while your own connection is fine, that is one of the rare cases where an APN adjustment is relevant — get in touch and we will walk you through it.
Usually not. CDJapan Rental runs system maintenance from Tuesday night into Wednesday morning Japan time, and QR code generation can be delayed during that window. If you ordered in that period, refresh after around 9:00 on Wednesday morning. Outside those hours, contact us with your order number.
Refunds are available before the eSIM has been activated. Once it is activated, it cannot be refunded — which is another reason to contact support before you start deleting and reinstalling things. If the problem is on our side, we will sort it out with you.
Yes, as long as you can get onto WiFi to complete the purchase and install — the airport, your hotel or a convenience store will all do. Purchases are processed 24 hours a day, including nights and holidays, so you are not waiting for an office to open. Buying before departure is still smoother, since you land already connected.
If your eSIM is not working in Japan, the odds are strongly in favour of a settings issue rather than a broken product — and specifically, of mobile data still pointing at your home SIM. Work down the eight checks in order, restart the phone between changes, and resist the urge to delete anything.
If you are still offline after all eight, that is genuinely worth an email rather than another hour of fiddling. Find any WiFi, gather the four items in Step 2 above, and send them to whoever sold you the eSIM — if that was us, we will take it from there.
For a deeper dive into plan mechanics — how data allowances are calculated, buying multiple eSIMs, adding data mid-trip — see our advanced Japan eSIM Q&A. If you are entirely new to eSIMs, start with the beginner's guide, and our step-by-step setup guide covers installation on both iPhone and Android.
Travelling to Japan soon? Get connected before you land.
CDJapan Rental is a Japan-based company offering eSIMs on the docomo network, with instant QR code delivery and English-speaking support based here in Japan.
