Japan's network quality
Japan has one of the best mobile networks on the planet. NTT Docomo, SoftBank, and au (KDDI) have built out deep LTE coverage across the country, including most rural areas. Shinkansen rides through the mountains, ferry terminals on small islands, ski resorts in Hokkaido: the signal is usually there. 5G is well established in Tokyo, Osaka, Nagoya, and Kyoto.
The point of saying this is: a good eSIM plan will fully take advantage of Japan's speeds. A bad one, routed through a weaker partner carrier, will not. Speed matters more in Japan than in many other destinations.
Why physical SIMs got harder
Post-2023, most of the tourist-focused physical SIM options at Narita and Haneda disappeared. IIJmio, B-Mobile, and similar prepaid data SIMs that once lined the shelves in airport convenience stores became harder to find or were discontinued for short-term visitor use. If you're counting on buying a SIM at the airport, confirm availability before your trip because what existed two years ago may not still be there.
eSIM has become the cleanest option for most visitors. Activate before you land, and you have data the moment you step off the plane.
What to look for in a Japan eSIM plan
Speed: look for plans that connect to Docomo or SoftBank networks directly rather than through slower reseller routes. Plans advertising "high speed" sometimes mean unrestricted LTE; others use it as marketing. Check user reviews for actual speeds.
Hotspot: Japan is walkable and transit-friendly, but if you're traveling with someone who doesn't have their own plan, or if you need to check a laptop occasionally, you need hotspot support. Many Japan plans disable it. This is the most common source of frustration, so verify before buying.
Rural coverage: Tokyo, Osaka, Kyoto, and Hiroshima are completely fine with any plan. Tohoku, Hokkaido, the Kii Peninsula, and remote islands are where coverage starts to vary. The main Docomo network covers most of rural Japan, so plans on Docomo tend to do best outside cities.
How much data do you need?
Japan is extremely walkable and Google Maps is your constant companion. Navigation in Tokyo's subway system alone burns data. For a typical one to two week trip with sightseeing, expect 5-10 GB. If you're doing long driving trips with constant navigation (Hokkaido road trip, for example), budget toward 10-15 GB.
Cherry blossom season (late March to early April) and ski season (December to February) are peak periods. Popular apps and providers raise prices or sell out of certain plans. Buy early if your travel coincides with either.
Tokyo vs Kyoto vs Osaka vs everywhere else
All three major cities have excellent coverage from every reasonable provider. The distinction only matters once you're heading to the countryside. Nara, Hiroshima, Nikko: all fine. Shirakawa-go, the Iya Valley, remote parts of Shikoku: still mostly fine, but check coverage maps if you're planning to spend significant time there.
See current plan options and pricing on the Japan eSIM page.