Source: 4 official provider pagesChecked 12 Aug 2026

Japan eSIM Comparison: Unlimited Plans, Networks and Start Dates

Comparison tables for Japan eSIMs mostly line up gigabytes against prices. That's the easy part. The differences that actually cost you something sit outside those columns: what each provider means by "unlimited," when your days start counting, whose network you end up on, and whether tethering is promised in writing.

This guide compares four providers on those four points, using only what each company publishes on its own site.

A note on prices before we go further: two providers quote in yen and two in US dollars, and all figures below are the prices displayed on 2026-08-12. Exchange rates move, and so do promotions, so treat cross-currency comparisons as approximate and check the current figure before you buy.

"Unlimited" Means Four Different Things

Every provider here sells something called unlimited. None of them mean the same thing by it.

Ubigi publishes its ceiling. Its unlimited plans come with a stated high-speed allowance — 25GB on the 7-day plan, 30GB on the 15-day, 60GB on the 30-day — after which the connection drops to 2Mbps. Priced at $25, $39 and $65 respectively.

Sakura Mobile's 3GB/day plan publishes a daily one. You get 3GB of high-speed data per day; past that, the connection drops to 200Kbps until the next day. Plans run from one to 90 days, starting at ¥1,500 (¥1,650 including tax), with 10% off if you buy two or more. Its separate Unlimited eSIM runs 1–31 days.

Airalo does not publish a ceiling. Its Japan plans are listed as "UnlimitedGB" with no stated high-speed allowance and no stated post-cap speed. Prices run ¥1,900 for 3 days, ¥2,800 for 5, ¥4,400 for 7, ¥5,650 for 10, ¥7,850 for 15 and ¥11,250 for 30.

Japan Wireless does not publish one either. Its plan page refers to a Fair Usage Policy and mentions a high-speed allowance tied to tethering use, but gives no figure. 5G Unlimited runs $16.63 for 2 days, $20.79 for 3, $35.35 for 7, $62.39 for 14 and $83.19 for 30. The 4G LTE Unlimited line is cheaper: $5.20 for 1 day, $29.12 for 7, $74.88 for 30.

So the four split two and two: Ubigi and Sakura Mobile tell you where the limit is, Airalo and Japan Wireless do not.

What the Throttled Speeds Actually Mean

Two numbers appear above — 2Mbps and 200Kbps — and they are not close to each other.

As a general guide to what those speeds allow: 2Mbps is roughly enough for maps, messaging, email and standard-definition video, though it will feel slow on image-heavy pages. 200Kbps is a different category. At that speed, messaging and basic text still work, but map tiles load slowly and video is not realistic.

This is a statement about the speeds themselves, not about any provider. A daily cap that resets each morning behaves very differently from a trip-long allowance, and which one suits you depends on how you travel rather than on which company is better.

Also worth knowing: a provider that publishes no cap is not the same as a provider with no cap. Airalo and Japan Wireless simply don't state one, and Japan Wireless explicitly references a fair usage policy. We have no basis for saying what happens past any threshold on those plans, so we won't.

When the Clock Starts

This is the difference most likely to cost you actual days, and it barely appears in comparison tables.

• Ubigi activates automatically on arrival in a covered destination
• Japan Wireless states its plans activate "automatically when you arrive in Japan and turn on data roaming"
• Airalo tells you to install whenever you like, and connect once you arrive — the connection is made by you, after landing
• Sakura Mobile depends on which plan you buy. Its 5G eSIM starts after you arrive in Japan. Its 3GB/day eSIM counts the day you install it as day one

That last line is the trap. Install a 7-day plan three days before you fly, and on the wrong product you have four days of coverage left when you land.

The safe habit, whichever provider you pick: install the eSIM before you travel, but do not assume installing is the same as starting. Read the specific product's wording, because within a single company it can differ between plans.

Which Network Are You Actually On?

An eSIM is a reseller arrangement — you are riding on a Japanese carrier's network. Which one is a reasonable thing to want to know, and providers differ in how plainly they say it.

Three of the four name their carriers outright. Airalo names one and leaves the other unstated.

Whether that matters is your call. If you are staying in major cities it is unlikely to be decisive. If your itinerary runs well outside them, knowing which network you're on lets you check that carrier's own coverage map before you commit — and you can only do that if you know the name.

Tethering: What Each Provider States

All four address tethering somewhere. The differences are in where they say it and what conditions they attach.

• Sakura Mobile states on the product page that hotspot and tethering are "fully supported," on both of its plans
• Ubigi states "Data sharing allowed" on the plan page
• Japan Wireless states hotspot sharing is supported on all 5G Unlimited plans — a scope limit worth noticing, since the company also sells 4G and fixed-data lines
• Airalo covers it in its help centre rather than on the product page, and conditionally: you can use your personal hotspot "as long as it is supported by your device and the network"

If tethering is central to your trip — sharing to a laptop, or to a travelling companion's phone — the practical difference is how much certainty you get before you pay. Two providers state it plainly on the page you buy from. One states it for a specific plan family. One states it in a separate help article, with conditions.

How to Choose

Rather than name a winner, here is the mapping from your situation to the feature that decides it. Match your case, then check the current pages for the providers that fit.

If you need to know your limit before you leave. Choose a provider that publishes a high-speed cap. Two of the four do: one as a per-trip allowance, one as a daily allowance that resets. A published number lets you plan; an unpublished one means you find out in Japan.

If you are a heavy user on a short trip. A daily-reset cap protects you from spending the whole allowance in the first 48 hours. A trip-long allowance gives more freedom on any single day, but nothing resets it once it's gone.

If your route leaves the big cities. Prioritise providers that name their carrier, then check that carrier's own coverage map for your destinations. This narrows the field to three.

If you will tether to a laptop or share with someone. Prefer a provider that states tethering support on the product page itself, and check whether the statement covers the specific plan you're buying rather than only part of the range.

If you are installing well before departure. Check that specific product's start rule. Prefer wording that says activation happens on arrival in Japan over wording that counts from installation — or install later.

If you are comparing prices across providers. Convert to one currency first, on the day you buy. Two quote in yen and two in US dollars, so the cheapest-looking option depends partly on the exchange rate at that moment.

Planning Checklist

• Decide whether you need a published high-speed cap or can accept an unstated one
• If you need a cap, decide between a daily reset and a trip-long allowance
• Check the start rule for the exact plan you're buying, not just the provider
• Install before you fly, but confirm that installing does not start the clock
• If you're leaving the major cities, check the named carrier's coverage map
• If you'll tether, confirm the statement covers your specific plan
• Convert prices to a single currency on the day you buy

Before You Go

All figures on this page are the prices and terms displayed on each provider's official pages on 2026-08-12. eSIM pricing changes frequently and promotions come and go, so confirm the current figure before you buy.

Two things this guide deliberately does not tell you: how fast these connections actually are, and how reliable they are in practice. We have not tested them. Everything above is what each company publishes about its own product, which is a useful basis for narrowing a shortlist and a poor basis for predicting real-world performance.

Where a provider does not publish something — a high-speed cap, a post-cap speed — we've said so rather than estimated it.

Sources: Airalo Japan eSIM · Ubigi Japan data plans · Sakura Mobile Travel eSIM · Japan Wireless eSIM plans (all checked 2026-08-12)

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