Pocket WiFi or eSIM in Japan? Saily vs Airalo Compared

Renting a pocket wifi in Japan used to be the standard answer for international travelers. Rental companies such as Japan Wireless hand you a small router at the airport or send it to your hotel. That still works in some situations, but for most travelers today an eSIM is faster and cheaper. I compared published network tests, read the terms of the major providers and used Airalo myself in Japan.

Japan runs on three major networks: NTT Docomo, KDDI au, and SoftBank. Docomo has the best coverage, including rural areas, mountain routes, and the slower Shinkansen lines outside the main Tokaido corridor. That matters for a pocket wifi router as much as for an eSIM, because the network underneath decides what you get. For the trains themselves, see my JR Pass guide.

The two eSIMs I recommend for Japan

Saily, the best coverage on Docomo

Saily runs on NTT Docomo. Right now it offers one of the better value packages: 20 GB for a flat price, with an app that does not get in the way. Setup takes a few minutes: download the eSIM right after purchase, activate it when you land. You don’t have to pick up a router at the airport, wait in a queue or return anything at the end.

Docomo’s coverage reaches well beyond Tokyo and Osaka, into rural routes, smaller towns and mountain areas. That matters on a Japan trip where you move around a lot.

If your route takes you well beyond the big cities, Saily is the one I would pick. With my code MOCHIMILES you get 10% off. It is applied automatically at checkout when you buy through my link, and if it is not, you can simply type it in yourself.

Airalo, the fastest option and the one I used myself

Airalo is the one I have used myself in Japan. I had it set up in minutes, the connection held up throughout the trip, and in independent network tests it came out as the fastest option at 141.6 Mbps on average. It runs on au and SoftBank rather than Docomo.

Airalo is just as good a pick, especially if most of your trip runs through Tokyo and Osaka. Setup was really easy and I was very happy with it. The one difference is the network: au and SoftBank are thinner than Docomo on rural routes and in the mountains, so if your trip goes far off the main lines, Saily has the edge there.

If you go with Airalo: new customers get 15% off their first eSIM with the code NEWTOAIRALO15. Unlike with Saily, the code is not applied automatically, so you have to enter it at checkout yourself.

Saily vs Airalo in Japan, compared

Both are good picks, and either beats renting a pocket wifi router for a solo traveler or couple. The difference comes down to your route: Saily’s Docomo network is the stronger choice for rural areas, smaller towns and mountain routes. Airalo is faster in the cities, and it is the one I used myself without any issues.

What I think of the other providers

Mobal, if you need a Japanese phone number

Mobal runs on KDDI au and is the only provider here that gives you a real Japanese phone number. Some hotels, restaurants that require reservations, and local services only accept calls from Japanese numbers. If that applies to your trip, Mobal is the right choice.

For a data-only connection, though, Mobal is slower: 24.8 Mbps in tests compared to over 140 with Airalo. The voice SIM setup is also more involved, with ID upload, postal delivery, and a waiting period. If you do not specifically need a local number, Saily or Airalo will serve you better.

Ubigi, solid but vague on pricing

Ubigi also runs on NTT Docomo and scored 73.7 Mbps in tests, with smooth video calls throughout. Setup is as fast as Airalo. On a purely technical level it is in the same category as Saily, and faster than any pocket wifi rental.

The reason I do not put it at the top: pricing and terms are not publicly listed, which makes it hard to compare directly. If Saily is unavailable for your dates, it is worth a look, but expect to dig for the details.

Sakura Mobile for groups and longer stays

Sakura Mobile runs on Docomo and offers flexible plan lengths: 1 to 90 days, plus Japan SIM card options and pocket wifi rental. If you are traveling in a group and want to share one connection, or staying long enough that a monthly plan makes more sense, it is a real option.

For a typical two-week trip with an eSIM-compatible phone, I would still go with Saily or Airalo. But Sakura Mobile covers cases those two do not.

Holafly, which I would skip

Holafly markets an unlimited plan, but the hotspot is capped at around 500 MB per day. Traffic runs through servers in Singapore, Hong Kong, and Poland, which can block some Japanese services including local streaming and certain platforms.

Coverage held up in cities in tests, but was noticeably weaker on rural routes and along slower Shinkansen lines. If you are choosing between Holafly and a pocket wifi router, the router is the better call. I would not buy Holafly myself.

Pocket wifi or eSIM in Japan: which should you get?

For years, a rented router from the airport counter was the default. You picked it up at arrivals, shared it with whoever you traveled with and returned it before departure. It worked, and coverage was generally solid.

The downsides of a pocket wifi rental have become harder to ignore. You are carrying an extra device, keeping an extra battery charged, and paying a daily rental fee plus a return fee. If the router runs out of charge on a long day out, everyone in the group loses internet at once. Lose or damage the device, and the replacement fees add up fast.

For most solo travelers and couples, an eSIM gets rid of all of that. You install it before you leave, activate it when you land, and there is nothing to give back.

A pocket wifi rental in Japan still makes sense in one situation: groups of three or more splitting the cost of one connection. If you are traveling with a family or a larger group and not everyone has an eSIM-compatible phone, a shared pocket wifi router often works out cheaper per person. Sakura Mobile covers that case well.

One option that used to come up often and rarely makes sense for tourists today: a Japan SIM card. Physical SIM cards require a compatible unlocked phone, often involve ID verification, and cannot be set up before arrival. An eSIM is faster and simpler for most international visitors.

Everyone else is better off with an eSIM than a pocket wifi. Which Japan eSIM to pick depends on your route: in the network tests, Saily wins on nationwide Docomo coverage and Airalo on speed in the major cities.

How to set up your eSIM before you leave

Most Japan eSIMs can be installed before you board and activated on landing. The steps are nearly the same with every provider:

1. Purchase the eSIM before your trip (with Saily, the code MOCHIMILES saves you 10%; new Airalo customers save 15% with NEWTOAIRALO15)
2. Follow the installation steps in the app or scan the QR code
3. Keep your home SIM active during the flight for boarding passes and last-minute messages
4. Switch to your Japan eSIM when you land or after you clear customs

Most phones from 2018 onward support dual SIM with eSIM, so you do not need to remove your home SIM and there is no router to return at the end of your trip. Check under “Mobile Data” or “SIM and Network” in your settings to confirm eSIM support before you buy. Information on device compatibility is available at the GSMA eSIM portal. iPhone XS and later, Samsung Galaxy S and Z series from 2019, and Google Pixel 3 and later all work.

When Airalo or Saily doesn’t work in Japan

Most issues with a Japan eSIM are solved in under two minutes.

eSIM installed but no signal

Check two things: Data Roaming is enabled on the eSIM line, and the eSIM is selected as your active data line in phone settings. Both are easy to miss during setup and are the cause of most no-signal reports.

QR code not scanning

A QR code for an eSIM can only be used once. If it has already been scanned, reinstall via the app manually using the activation code. Both Airalo and Saily allow this in their apps.

eSIM activated too early

Some plans count days from activation rather than first use. Install before you leave, but do not activate until you land. Check the terms of your specific plan before purchasing.

Phone does not recognize the eSIM

Even with an eSIM-compatible phone, some home carriers lock the device to prevent eSIM use from other providers. This is common with subsidized contracts. Contact your home carrier if the eSIM option does not appear in your settings at all.

Data running low

Both Airalo and Saily let you top up directly in their apps. In Airalo, tap the active plan and select a top-up package. In Saily, the option is in the plan overview screen. Both activate within minutes.

Quick answers

Do you need a Japanese phone number? Only if you are making reservations at restaurants that require local calls, or reaching local services by phone. Mobal is the only provider that covers this. For most trips, a data-only eSIM is enough, and a pocket wifi rental fee is not worth it just for that.

Will your phone work with a Japan eSIM? Most phones from 2018 onward do. Check your device specs before buying. You do not need a pocket wifi rental if your phone supports eSIM.

When should you activate? Install before you board, activate when you land. Do not activate at home if your plan counts days from activation rather than from first use.

I use Google Maps constantly in Japan, and the vegan konbini guide is far more useful with mobile data on hand. A handful of Japanese phrases for the konbini also go a long way when the app is not quite enough. If you are also planning your transport, the JR Pass guide covers trains, Suica, and airport routes.