Does a Japan eSIM work in Hokkaido, Okinawa, the mountains and on the Shinkansen?
Japan's 5G reaches 98.6% of the population, 98.9% in Hokkaido and 99.9% in Okinawa, and every Shinkansen tunnel has been covered since 2020. The exceptions: high mountains out of season, and Russian networks near Shiretoko.
Yes, almost everywhere people travel. At the end of March 2026, 5G reached 98.6% of Japan's population, 98.9% in Hokkaido and 99.9% in Okinawa, according to figures from the Ministry of Internal Affairs and Communications. Every Shinkansen line has had coverage in its tunnels since December 2020. The exceptions are the high mountains outside the climbing season, and one corner of Hokkaido where your phone can pick up Russian networks.
Our Japan eSIM connects to docomo, au, SoftBank and Rakuten Mobile, so it uses whichever of the four reaches you.
Region by region
| Area | What to expect |
|---|---|
| Tokyo, Osaka, Kyoto and the cities | full coverage, 5G widely |
| Hokkaido | 98.9% of the population covered by 5G, gaps in remote parks |
| Okinawa | 99.9% of the population covered by 5G |
| Japan Alps and Daisetsuzan | seasonal mountain stations, mid April to mid November |
| Shinkansen tunnels | covered on every line since 2020 |
Hokkaido: Shiretoko and the Russian networks
In Rausu and on the Shiretoko Pass, phones can connect to Russian networks across the water. The Rausu tourist association advises turning off automatic network selection there. With a travel eSIM, set the network manually to a Japanese one (docomo, au or SoftBank) before you drive the pass, so you do not roam onto a Russian network.
Mountains
docomo opens seasonal base stations on climbing routes from around mid April to mid November, and says coverage in Daisetsuzan varies a lot by season, with some spots hard to use at night. Outside the season, plan high routes as offline. Mount Fuji has its own seasonal coverage, up to the summit.
On the train
All Shinkansen tunnels are covered on docomo, au and SoftBank: the Tokaido line since 2002, the rest of the network since 2020. There is also free Wi-Fi on board: "Shinkansen_Free_Wi-Fi" on the Tokaido, Sanyo and Kyushu lines, and JR-East's Wi-Fi on the Tohoku, Joetsu, Yamagata, Akita and Hokkaido lines.
Free Wi-Fi as a backup
The Japan Wi-Fi auto-connect app signs you into many free hotspots in airports, major stations and convenience stores with one registration. Useful as a backup, though sessions are usually time limited.
Quick answers
Does a Japan eSIM work in Hokkaido?
Yes, in towns and on the main roads. 5G covers 98.9% of Hokkaido's population. Remote parks have gaps, and near Shiretoko you should select a Japanese network manually.
Does a Japan eSIM work in Okinawa?
Yes. 5G covers 99.9% of Okinawa's population.
Is there signal on the Shinkansen?
Yes, including in tunnels, on every line since 2020, plus free Wi-Fi on board.
Is there signal in the Japan Alps?
On climbing routes, docomo runs seasonal base stations from mid April to mid November. Outside the season, plan for gaps.
Sources: Ministry of Internal Affairs and Communications 5G coverage figures via Jetstream (27 July 2026), Rausu Tourism Association, docomo mountain coverage pages, Nagano Prefecture (2025), MIC Tohoku Bureau and KDDI (June 2020), Railway Pressnet, JR Central, NTT Broadband Platform. Checked 21 September 2026.