Best eSIM for Japan 2025: IIJmio, Mobal and Airalo Compared

Japan's mobile network coverage is extraordinary (NTT Docomo alone reaches 99.9 pct of the populated landmass) but buying the wrong eSIM before you fly can cost you double, leave you throttled on day three, or strand you without a usable number. Here is a direct comparison of the three options most travellers actually use in 2025: IIJmio, Airalo, and Mobal.

IIJmio: the local pick for short trips

IIJmio is a Japanese MVNO running on Docomo's backbone, and it shows. The 15-day 15 GB plan costs roughly 1,800 yen (about $12 USD), which is the best data-per-yen ratio on this list. You buy it at iijmio.jp before departure, receive a QR code instantly, and scan it on your device at home: no airport queuing.

The catch: IIJmio offers data-only. No voice number, no SMS to Japanese services. That is fine for maps, translation apps, and messaging over Wi-Fi, but it breaks any service that sends an SMS verification code to a Japanese number: some hotel Wi-Fi portals, certain ticketing apps, or JR East's Ekinet reservation system. If you need SMS, look elsewhere.

Speed is capped at 200 Mbps on LTE, and IIJmio enforces a fair-use throttle once you burn through your data bucket. In practice, throttled speeds hover around 200 Kbps: slow for video, workable for maps.

Airalo: the international traveller's default

Airalo's Japan eSIM (branded "Digi Japan") runs on SoftBank infrastructure and sells globally through the Airalo app. The 20 GB / 30-day plan costs around $21 USD (roughly 3,200 yen at current rates). For a trip under two weeks you can also grab a 3 GB / 7-day plan for about $7.

The real advantage is the Airalo app itself: you can top up, monitor usage, and install the eSIM from any country without creating a Japanese account. That makes it the safest choice for spontaneous Japan trips or travellers who book late.

SoftBank coverage is slightly thinner than Docomo in rural Tohoku and mountain areas. If you are hiking the Kumano Kodo or staying in remote onsen towns, IIJmio on Docomo is the safer network bet. For Tokyo, Kyoto, Osaka, and the Shinkansen corridor, Airalo is indistinguishable from a local SIM.

Like IIJmio, Airalo Japan eSIMs are data-only. Calls route through WhatsApp, FaceTime, or Line.

Mobal: the only option with a real Japanese number

Mobal is the outlier. It sells a Japan eSIM that includes an actual Japanese phone number with inbound calls and SMS: the only widely available eSIM for tourists that does this. The unlimited data plan runs around 4,000 yen per month (billed in USD at roughly $27).

"Unlimited" is soft-capped: Mobal throttles heavy users after 3 GB of high-speed use in a single day, though average travel use rarely triggers this. The network is Docomo-sourced, so coverage matches IIJmio.

The Japanese number matters in specific scenarios: booking a ryokan that requires a local callback number, registering for IC card apps like Suica on iPhone, or verifying identity on Japanese platforms. If none of those apply to your trip, the price premium is hard to justify.

Which one should you buy?

• Two weeks or less, data only: IIJmio 15-day 15 GB. Cheapest, fastest network, zero friction if you have a Docomo-compatible device (most modern flagship phones qualify, check the IIJmio compatibility list).
• Longer trips or uncertain dates: Airalo 30-day plan. Easier to manage internationally, SoftBank is perfectly adequate in cities.
• Need a Japanese phone number: Mobal. Full stop. No other eSIM for tourists offers this.

All three eSIMs support emergency calls to 110 (police) and 119 (ambulance/fire) at no charge, even with zero data balance remaining. Verify eSIM compatibility at home before you leave: most iPhone 12 and newer models and flagship Android devices from 2021 onward support dual eSIM, but budget handsets often do not.