Japan is a country where you use your phone constantly — maps, train times, camera translation. Here is the cheapest way to keep it fed.
For a trip of a few days to a few weeks, a travel eSIM is the cheapest and simplest option in Japan: day passes from about $1.29, or roughly $7 for 10 GB over a month, on docomo, SoftBank or au. Pocket WiFi costs several times that and has to be collected and returned; a carrier roaming pass costs about ten times that. Free WiFi exists but is far patchier than visitors expect.
Plan prices are ours and current; rental and carrier prices vary — check yours.
More than most destinations. Navigation runs constantly, train apps get checked at every transfer, and camera translation on menus and signs is bandwidth-hungry in a way people do not anticipate. Realistic budgets:
Download offline maps for Tokyo, Kyoto and Osaka before you go and you will cut this meaningfully.
Japan's three networks are among the best in the world. You will have signal on the shinkansen for most of the route, in the Tokyo and Osaka subways, and in rural Hokkaido and the Japanese Alps far more reliably than the equivalent in Europe or the US. Long tunnels and some mountain hiking trails are the exceptions.
A travel eSIM, for almost every trip. Day passes start around $1.29 and a 10 GB month-long plan is about $7 — against roughly $5–10 a day for pocket WiFi rental and $10–15 a day for a carrier roaming pass. The only cheaper option is a local prepaid SIM, which costs you a counter visit and your own SIM coming out.
Less than visitors expect. Convenience stores, major stations, Starbucks and many hotels have it, but it is often registration-walled, English-optional and unusable while walking. Do not plan a trip around it — Japan is a country where you use maps and translation constantly.
NTT docomo, SoftBank or au/KDDI depending on the plan. All three have excellent urban and rural coverage, including most of the shinkansen route and the Tokyo and Osaka subway systems.
Around 3–5 GB for most people. Japan skews data-heavy because of constant navigation, train apps and camera translation — Google Lens on a menu is not free. If you tether a laptop or video call home, budget 10 GB.
Tapping through a gate works offline. Topping up the card needs a connection, so a dead data plan means you can still travel until the balance runs out, then cannot reload without WiFi.
You can, but you will pay tourist-counter prices and queue after a long flight, and at Haneda or Narita you will have already needed data to find the counter. Install before you fly and you are online on the train into the city.
docomo, SoftBank and au coverage. Delivered in minutes, install before you fly.
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