Japan eSIM plans compared

Which plan size fits your trip to Japan

Start with the validity period, then choose how much data you want to buy. Saily lists 1 GB for 7 days at US$3.99, while Yesim lists 1 GB for 30 days at US$4.44. The allowance is the same, but the time available to use it differs.

For a city trip where you want to keep a fixed data budget, compare allowances rather than buying unlimited by default. Yesim lists 5 GB for 30 days at US$10.56. Saily lists 10 GB for 30 days at US$17.99. These are different spending and data choices, not estimates of what your trip will consume.

If you want more room for rail days and day trips, Saily's 20 GB for 30 days costs US$24.99, or US$1.25 per GB, the lowest price per GB in our price table. Ubigi's 25 GB for 30 days costs US$32.00. Pick the extra allowance only if you expect to use it; a lower unit price does not mean a lower total bill.

Also consider what happens if you run low. Saily lets you add data through its app and offers auto top-up. Yesim lists balance top-up as unavailable. That difference matters if your plans change while you are away.

Unlimited plans and their limits

Compare unlimited plans over the same trip length. For 7 days, Airalo lists US$26.50 and Holafly lists US$27.50. For 15 days, Ubigi lists US$39.00 and Saily lists US$48.99. Price is part of the choice, but the speed and sharing terms also matter.

Saily gives you 5 GB per day at full 4G/5G speed, then reduces speed to 1 Mbps for the rest of the day. Saily describes that reduced speed as suitable for navigation, messaging, and standard browsing. If a rail day involves heavier data use, judge the plan by that daily full-speed allowance rather than the unlimited label.

Holafly says operators may apply a Fair Usage Policy in rare cases for no more than 1 day. Its hotspot allowance is separate: Holafly lets you share 1 GB per day. Saily describes hotspot sharing as limitless, but its unlimited plan still has the daily speed rule.

Yesim also warns that speeds may be reduced under the network operator's Fair Usage Policy. The provider pages we checked do not state a numerical fair-use threshold for Holafly or Yesim, or an unlimited-plan speed threshold for Airalo, Nomad, or Ubigi. Do not read an unspecified threshold as a promise of unrestricted full-speed data.

Networks and coverage

The network names on provider pages give you a more concrete comparison than a general coverage claim. Airalo describes its displayed network as the primary network the eSIM uses. The names listed for Japan are:

• Airalo: Softbank.
• Holafly: KDDI / Softbank.
• Saily: KDDI and SoftBank.
• Nomad: KDDI au / SoftBank.
• Yesim: SwitchLess Networks.

Before you fly

Saily names coverage across Tokyo, Kyoto, Osaka, Fukuoka, Sapporo, and other major cities. Holafly advertises 5G where available, plus 4G and LTE. Nomad says its eSIM can connect automatically to a local network and describes switching to another available network.

For rail travel and day trips, those statements are not route-level guarantees. The provider pages we checked do not establish coverage for a particular rail line or day-trip destination. Keep that distinction in mind when comparing named networks: a city coverage claim does not answer every question about the places between cities.

Before departure, read your chosen provider's installation and activation instructions. Airalo says you can install in advance with a stable internet connection. In the coverage area, turn the eSIM on and select it for data.

Nomad lets you buy and install ahead of time, but requires activation within 60 days of purchase. Its plan starts automatically when it connects to the destination network. Saily lists a 180-day activation period and automatic activation at your destination when the eSIM is on and roaming is enabled.

Holafly says its plan activates when the eSIM connects to a supported network. Yesim instructs you to install upon arrival, requires activation within 90 days of purchase, and starts validity upon connection to a compatible network. Follow the provider's timing rather than assuming installation and the start of your paid days are the same event.