🗾 Japan eSIM Comparison

Airalo vs AeroSims for Japan (2026): Up to 46% Cheaper Data — and Honest Unlimited Math

Updated July 2026 · Prices verified at provider checkouts and subject to change

Live video from Shibuya crossing, Google Maps through Kyoto's backstreets, a translation app open at every menu — Japan burns mobile data like almost nowhere else. Airalo is the world's biggest eSIM store and a fair benchmark, so we compared its Japan lineup against AeroSims line by line — including the one category where Airalo wins — so you can decide in two minutes.

Fixed data · 3–50 GB · valid 30 daysGet the Japan eSIM — 10 GB for $9.90 →

The price gap, in real trips

On a one-week Tokyo-and-Kyoto trip, most travelers use 1–2 GB per day — a 10 GB package covers it comfortably. That's $9.90 at AeroSims vs ~$18.00 at Airalo for the 30-day version: $8.10 saved, or 45%. Even Airalo's shorter 7-day edition of the same bundle (~$17.00, sold under its "Moshi Moshi" Japan line) barely closes the gap.

Over two weeks the pattern holds: 20 GB costs $16.90 vs ~$25.00 — about 32% less. And for a long stay, AeroSims sells 50 GB for $34.90 ($0.70/GB); Airalo's Japan lineup tops out at 20 GB, and even at its best listed rate (20 GB / 15 days at ~$24.00, about $1.20/GB) assembling the same 50 GB works out to roughly $60.

For context: our eSIM Price Index 2026 puts the global median at $3.18 per GB across 186 countries. AeroSims Japan at $0.99/GB is less than a third of that — Japan is one of the cheapest places on earth to buy eSIM data, if you buy it from the right shop.

The unlimited question — where Airalo genuinely wins on price

Here's the part a less honest comparison would bury: Airalo sells unlimited data for Japan, and it's cheaper than ours. As of July 2026 its unlimited tiers run $11.50 (3 days), $17.00 (5), $27.00 (7), $34.50 (10), $49.00 (15) and $69.00 (30). AeroSims unlimited starts at $7.92 for a single day and lands at $52.11 for a week or $6.29/day on a 30-day plan. On the sticker price, Airalo takes this category — full stop.

What the extra money buys is throughput and flexibility: AeroSims gives you 5 GB per day at full 4G/5G speed — two-thirds more than Airalo's 3 GB — with speed reduced afterwards until the daily allowance resets rather than pinned to a fixed 1 Mbps, plus all three Japanese networks including Docomo, and any trip length from 1 to 90 days instead of six preset tiers.

And there's a third option most unlimited-vs-unlimited comparisons skip entirely: the 20 GB package at $16.90. It's $10 cheaper than Airalo's week of unlimited, has no daily ceiling at all, and stays valid for 30 days. Unless you reliably burn through 3+ GB every single day, the fixed package beats both unlimited plans on pure economics. If the cheapest unlimited badge is genuinely all you're after — buy Airalo, and enjoy Japan. AeroSims' unlimited exists for the trips that break allowances: 4K uploads, tethered laptops, workations.

"Unlimited" fine print: the numbers behind both plans

Every unlimited travel eSIM has a fair-use policy — the difference is whether you learn the number before it matters. Credit where it's due: Airalo publishes its fair-use policy openly — 3 GB per day at full speed, then 1 Mbps until the allowance resets 24 hours after activation. AeroSims' Japan unlimited plans come with 5 GB per day at full 4G/5G speed, with reduced speed afterwards until the daily allowance resets — and we'd rather print that number right here than let you discover it mid-trip.

What the numbers mean in practice: 5 GB is roughly six hours of HD video or a full day of heavy navigation, uploads and video calls — a ceiling few travelers ever touch. 1 Mbps, on the other hand, still handles maps, messages and standard-quality music, but HD video, photo backups and hotel-room streaming will crawl. Most people use 1–2 GB per day and would stay under either limit; the difference only shows on the heavy days — which is exactly when you'll care.

Why not an airport SIM or pocket Wi-Fi?

Japan doesn't really do cheap airport SIMs. Prepaid SIMs with a phone number are effectively unavailable to tourists (residence and ID rules), and the data-only tourist SIMs in the vending machines at Narita and Haneda typically cost several times more per gigabyte than any eSIM. The classic alternative — pocket Wi-Fi rental — means a daily fee, a pickup counter after a 12-hour flight, a second device to keep charged every night and a return deadline hanging over your last morning. An eSIM installed at home is working before you clear customs.

Coverage: Tokyo to the countryside

The AeroSims Japan eSIM connects to NTT Docomo, SoftBank and au by KDDI with automatic switching — 5G in the Tokyo and Osaka metros, solid 4G along the Shinkansen corridors, and Docomo's famously deep rural footprint for onsen towns, the Japanese Alps, Hokkaido and the smaller islands. Airalo's Japan plans run on SoftBank and KDDI — perfectly good in the cities and along the main tourist trail; the practical difference appears when your itinerary leaves it.

Japan eSIM questions travelers ask

Is AeroSims really cheaper than Airalo for Japan?

For fixed data, yes — 32–46% depending on size (5 GB: $5.90 vs ~$11.00; 10 GB: $9.90 vs ~$18.00; 20 GB: $16.90 vs ~$25.00). For unlimited, no: Airalo's unlimited is cheaper per day, with a 3 GB daily full-speed allowance against AeroSims' 5 GB. We'd rather show you both numbers than hide one.

What does "5 GB/day at full speed" mean in practice?

Each day of an AeroSims unlimited plan you get 5 GB at full 4G/5G speed; beyond that, speed is reduced until the next day. Most travelers use 1–2 GB per day, so the limit is rarely felt — the point is that you know the number up front.

What happens after Airalo's 3 GB per day?

Airalo's published fair-use policy reduces speed to 1 Mbps for the rest of the day, restoring full speed when the allowance resets. That's fine for maps and messaging, but slow for HD video or uploading a day's photos.

Do I need a passport for an eSIM in Japan?

No. Japan's ID and residence requirements apply to physical SIM cards with phone numbers. A travel data eSIM needs no ID at all.

Does my WhatsApp number keep working?

Yes. The eSIM is data-only; your home SIM stays installed for calls and SMS codes, and WhatsApp keeps your existing number.

When does the plan start counting days?

When the eSIM first connects to a Japanese network — not at purchase. Install it at home days before you fly and lose nothing.

Where can I read more about Japan connectivity?

See the full AeroSims Japan eSIM guide for networks, activation steps and itinerary tips.

Bottom line

Same country, both sets of fine print on the table — and a clean split. Airalo owns the cheap-unlimited niche in Japan, and if that's your one criterion, buy it there. For everything else, AeroSims sells the actual gigabytes for roughly a third to a half less, on all three Japanese networks, with 30-day validity, a 50 GB option Airalo doesn't offer, and an unlimited plan with the higher daily full-speed allowance for the travelers who truly need it. For Japan in 2026, the math points one way.

Install today · Activates when you land in JapanGet the Japan eSIM — unlimited · 5 GB/day full speed · from $6.29/day →

Prices checked July 2026 at aerosims.com and airalo.com and cross-checked against independent eSIM listings; both change with promotions and currency. Per-day and per-GB figures derived from listed plan prices. Airalo fair-use details (3 GB/day at full speed, then 1 Mbps) from Airalo's published Unlimited Data Fair Use Policy at the time of writing. AeroSims unlimited allowance (5 GB/day at full 4G/5G speed, reduced afterwards until the daily reset) per AeroSims plan specifications.