Prices in this article were read off each provider’s own Japan page on 14 September 2026.
The answer, first
Buy an unlimited plan on KDDI’s au network for a normal 7–15 day city trip. Sim Local lists 7 days at $19 and 10 days at $26 on its Japan page, and au is the network that hands out the fastest 5G downloads in Japanese cities. Buy metered NTT Docomo capacity instead if you are driving into mountains or moving between small towns: Ubigi’s 10 GB / 30-day plan costs $16.50, and Docomo reaches further than au or SoftBank.
Need a Japanese phone number that can receive SMS? Mobal is the only mainstream provider here that sells one to short-stay visitors. Phone carrier-locked? None of this will install — rent a pocket Wi-Fi and skip the rest of the page.
Everything below is the working detail: the per-gigabyte arithmetic, the throttle numbers buried in provider terms, and the handful of points where hands-on tests flatly contradict each other.
Three checks before you pay anyone
1. Is the handset unlocked? Apple’s own documentation is blunt about it: Dual SIM with an eSIM needs “an iPhone XS, iPhone XS Max, iPhone XR, or later”, a carrier that supports eSIM, and — for two different carriers — an unlocked phone. A carrier-locked handset can only roam on its own operator or use a hotspot.
You can find out in under a minute. On iPhone, open Settings → General → About and read the Carrier Lock line; “No SIM restrictions” means you’re free. On Android, go to Settings → Network & Internet → Mobile network and switch off Automatic network selection; if more than one carrier appears, you’re unlocked.
2. Does the hardware speak eSIM? Dial *#06#. If an EID number comes back, your device has an eSIM chip and is ready. Windows laptops: Settings → Network & Internet, and look for the Cellular entry.
3. How much data do you actually burn? Plan a floor of 1 GB per day and build from there. Maps, messaging and ticket checks sit near the bottom of that; photo-heavy days, cloud video uploads and laptop tethering blow straight through it. Anyone who streams video in the evening should be shopping for either a big metered plan or an unlimited one, not a 3 GB top-up.
The per-gigabyte math nobody prints
Providers advertise total price, because total price looks small. Convert to a unit rate and the tiers collapse into a very simple ladder. Saily’s own Japan page, read on 14 September 2026:
| Saily plan | Price | Per GB |
|---|---|---|
| 1 GB / 7 days | $3.99 | $3.99 |
| 3 GB / 30 days | $7.99 | $2.66 |
| 5 GB / 30 days | $10.99 | $2.20 |
| 10 GB / 30 days | $17.99 | $1.80 |
| 20 GB / 30 days | $24.99 | $1.25 |
Ubigi’s 10 GB / 30-day plan works out at $1.65 per GB. Mobal, which quotes in yen, runs ¥1,650 per GB at its 1 GB tier and drops to ¥105.60 per GB at 50 GB (¥5,280) — a 15.6× swing inside one price list, which is why the smallest tier on any provider is the worst possible purchase for a two-week trip.
Unlimited plans convert differently, so convert them to cost per day instead. On 14 September 2026 the ten-day rate was $2.60 a day with Sim Local, $3.45 with Airalo and $3.65 with Holafly. That is the real question: not “unlimited or metered”, but “will I use more than one and a quarter gigabytes a day”, because below that line a 20 GB metered plan is cheaper than every unlimited plan on the market.
| Provider | Plan | Price | Unit rate | Checked |
|---|---|---|---|---|
| Sim Local | Unlimited, au/KDDI, 7 days | $19.00 | $2.71/day | 14 Sep 2026 |
| Sim Local | Unlimited, au/KDDI, 10 days | $26.00 | $2.60/day | 14 Sep 2026 |
| Sim Local | Unlimited, au/KDDI, 30 days | $77.50 | $2.58/day | 14 Sep 2026 |
| Airalo | Unlimited, 10 days | $34.50 | $3.45/day | 14 Sep 2026 |
| Airalo | Unlimited, 30 days | $69.00 | $2.30/day | 14 Sep 2026 |
| Holafly | Unlimited, 10 days | $36.50 | $3.65/day | 14 Sep 2026 |
| Holafly | Unlimited, 30 days | $73.90 | $2.46/day | 14 Sep 2026 |
| Saily | Unlimited, 15 days | $48.99 | $3.27/day | 14 Sep 2026 |
| Saily | 20 GB / 30 days | $24.99 | $1.25/GB | 14 Sep 2026 |
| Ubigi | 10 GB / 30 days | $16.50 | $1.65/GB | 14 Sep 2026 |
| Mobal | 50 GB / month (data only) | ¥5,280 | ¥105.60/GB | 14 Sep 2026 |
Prices move. A hands-on review of Japanese eSIMs quoted a 7-day unlimited plan at $22.50 and a 10-day plan at $29; Sim Local’s live page now says $19 and $26 for the same product shapes. If a price has no date next to it, treat it as decoration.
What “unlimited” means at the bottom of the barrel
Read the terms, not the headline. Three patterns are worth knowing before you buy.
Throttling to unusable. Mobal’s own plan page says that once you exhaust the monthly allocation, speeds drop to “around 200 Kbps”. That is below the threshold where map tiles load comfortably. Mobal’s advantage is that the connection never dies; it is not that the connection stays fast.
A daily high-speed bucket. Saily states its unlimited plan plainly: 5 GB a day at full speed, then unlimited data capped at up to 1 Mbps. That is a workable allowance rather than a trick — but it is not what the word “unlimited” suggests on the pricing card.
One to three gigabytes a day, then a wall. The cheap end of the unlimited market usually allows only 1–3 GB of daily high-speed data before throttling kicks in. A 10 GB-per-24-hour allowance is a genuine outlier, and a provider offering it is worth paying a little more for.
Tethering deserves its own check. Holafly’s Japan page allows sharing of 1 GB per day, scaled to trip length — a 7-day plan carries 7 GB of shareable data. Some plans block hotspot use entirely. If a laptop is coming with you, the hotspot row of the plan table matters more than the download headline.
Which network you land on decides more than the brand
Japan runs on three networks, and the choice between them is geographic rather than qualitative.
NTT Docomo carries the widest footprint. Mobal’s page states that Docomo covers over 99% of Japan’s population, and the rural and mountainous gaps belong to whoever isn’t on it. KDDI (au) is the city performer — independent testing puts it at the front for 5G download speed in urban areas. SoftBank sits between the two as a dependable all-rounder.
Two practical consequences. First, a provider selling “unlimited 5G” is selling you the network underneath, so check which one the plan uses: the same brand can split its tiers — metered plans on one carrier, 5G-unlimited plans on another. Second, a 5G icon is not a speed guarantee. Japanese 5G is concentrated around Tokyo, Osaka and other large cities, and handsets frequently display 5G while delivering speeds that a good 4G connection would match.
Coverage claims also age. Ubigi’s product page today lists a combination of KDDI and NTT Docomo; earlier write-ups describe Docomo alone. Networks change under a brand without the brand changing its name.
Where the tests openly disagree
This is the part no comparison table will tell you, because the honest answer is that the field results contradict each other.
Mobal’s speed is genuinely unpredictable. One long-running test series rated Mobal’s upload speeds the fastest of four providers they had bought — averaging above 9 Mbps in Tokyo with peaks in the low twenties — while a separate six-device side-by-side test placed Mobal last and had to throw away its entire first day of data because the line was throttled at the time. Both cannot describe a stable product. What the disagreement actually tells you: Mobal’s performance swings more than its competitors’, and a single afternoon of testing tells you almost nothing about the brand.
“No caps” and the fine print can coexist. At least one provider publicly claims that no user has ever been throttled, while the same 30-day unlimited 5G product limits tethering to 30 GB in total. The headline is about the phone; the restriction is about the laptop.
Tethering has three positions in circulation. That it is simply included with no restrictions. That some eSIMs cannot share a connection at all and you must check the provider page. That everything supports it but most providers cap it. Holafly’s own numbers settle part of the argument — 1 GB a day of sharing — which means the “check before you buy” advice is the correct one.
City navigation is contested. One guide calls Google Maps the single most useful tool in Japan, citing platform numbers, station exit numbers and in-app restaurant reservations. Another says explicitly not to use Google Maps on the Tokyo metro, because it makes mistakes and will not tell you which carriage to board. Both are true in their own lane: Google Maps for reservations and last-block walking directions, a dedicated transit planner when you need to arrive at the right escalator.
Data allowances are the quiet variable. Reports of what a light traveller needs range from 5 GB a week to 20 GB a week depending on streaming habits — and none of those estimates survive a tethering laptop.
Installing it: a five-minute job that fails in two predictable ways
The install itself is short. The failures are specific.
- Do it before you fly, on a stable connection. If the download drops mid-way, the profile install fails and you start over.
- Buy the plan, then tap download. The handset jumps to Settings — tap Activate when it appears.
- Do not close the screen or switch apps. Activation takes roughly a minute, and leaving the screen cancels it.
- Choose “Data Only” when the phone asks, then rename the line to something you will recognise. “Travel” and “Business” become indistinguishable after a fortnight of travel.
- Turn the new line on, then decide about your home SIM. Leave it on but switch mobile data off, or switch the line off entirely. The second option also stops calls and SMS to your normal number, while WhatsApp, iMessage and FaceTime continue over the eSIM’s data.
- Two hardware quirks to expect. An eSIM profile generally cannot be transferred between handsets once installed, and iPhones have an extra profile-download step that Android devices skip. A QR code also needs a second screen, or a long manual code typed by hand.
Details that never make it into a plan table
- Ubigi’s IP-location feature is free and documented on the provider’s own help page. Your traffic normally exits through an IP address from your country of residence, which keeps home streaming libraries and banking apps behaving; a single tap switches you to a local Japanese IP for Japan-only services. The switch requires a brief trip through Airplane Mode, and it is currently offered to residents of the United States, United Kingdom, Canada, France, Germany, Belgium, Switzerland, Australia, Singapore and Japan.
- You can buy a replacement plan with no connection at all, as long as the eSIM profile is already on the phone — no Wi-Fi, no active data, no roaming signal required. That matters on the day a plan expires while you are standing on a street corner without a PIN for a taxi app.
- A Japanese number is a regulated product, not a checkout option. Mobal’s number tiers need identity verification: you upload your ID, then either collect an activation code in Japan against your passport or wait for a physical letter, because email delivery is not offered for those plans. The number itself arrives only after activation inside the country.
- Mobal’s data allowance resets on the 1st of every calendar month, regardless of your start date. A plan running 25 April to 7 May therefore collects two allocations.
- If you leave Japan but want to keep the number, it can be parked in a low-activity mode for ¥900 a month rather than cancelled.
- Pocket Wi-Fi’s real cost is the battery. Many hotspot units run under six hours with several devices attached, their practical range is about 10–15 metres, and a group that splits up for the afternoon loses the connection entirely. Per-person eSIMs solve exactly that problem.
- Heavy users should run both, on different networks. A hotspot on one carrier plus an eSIM on another means a single outage cannot take the whole family offline, and remote valleys rarely fail both at once.
- Japan’s sockets are 100 V, Type A — the two flat parallel prongs. Two-prong devices from North America need no adapter; anything with a third pin does. Smaller city hotels frequently offer only two outlets, so a multi-port charger earns its luggage space.
- Carry roughly ¥10,000 in cash on arrival. Small shrines, temples and street vendors still run on notes even as card acceptance spreads.
- A transit-pass filter beats a fare calculator. Route-planning apps that accept your rail pass as a filter will only suggest the lines you have already paid for, which removes the platform-side guesswork on a JR pass day.
- Earthquake alerts arrive with about a minute of warning through dedicated alert apps, and they can be scoped to your region. You will probably never need it. The cost of installing it is ten seconds.
- *Type #06# before you leave the airport**, not after. A traveller discovering at the arrivals hall that the handset has no EID has also discovered that the whole plan was wasted.
Pick by trip shape, then stop reading
Ten to fifteen days, mostly cities: one unlimited au plan, installed before you fly, $26 for ten days. Rural driving, mountain towns, more than a week of trains: a metered Docomo plan, with a second carrier on a second device if your work depends on the connection. A number that receives SMS: Mobal, passport ready, and accept that the number arrives after you land. Carrier-locked phone: pocket Wi-Fi, no debate.
The data question is settled in about ten minutes. Where you sleep is not, and in Japan the two are linked — station proximity decides how much of your day the commute eats. Our Japan accommodation guides cover the areas that matter most for a first or second visit: 河口湖住宿推薦, 京都住宿推薦, Sapporo hotels, 上野住宿推介, 福岡住宿, and 名古屋住宿.
Get the network right and the trip stops being about logistics.