Short answer
It depends on the plan's operators and on the location. The plan page lists the operators stored for that plan, and NTT docomo, au, and SoftBank, between them, say to check their own coverage pages and say that service can fail on a mountain trail, in a tunnel or an underground station, or near the edge of a mapped area.
Fact table
As of 2026-10-20
Each claim names its source. The full source list, with the date each page was read, is below.
| Claim | Source |
|---|---|
| Wakamo keeps an operator name and a network type on a plan only when both are present. | Wakamo Japan plan page |
| On the plan page, the Network line for the plan you open shows the network type stored for that plan, and the operator names stored for that plan when it has any. When no generation is stored, the line says Network type not specified. | Wakamo Japan plan page |
| NTT docomo's service-area page says you can check where 5G and LTE service is available. Its prefecture search lists 47 prefectures, including Hokkaido and Okinawa. | NTT docomo, service area |
| NTT docomo publishes a search of mountain trails where a phone can be used. docomo says the spots are approximate and that radio conditions can make use difficult. The search result is dated 2025-09-02, when docomo updated the Hakusan map. | NTT docomo, mountain trails |
| NTT docomo's Tokyo-area subway page lists Tokyo Metro, Toei Subway, Yokohama Municipal Subway, and the Minatomirai Line, and says you can check which stations can use 5G and LTE. The page is current as of 2026-06-30. docomo says some places inside a station may be unusable, and points to the service-area map for the service area. The page does not name a Shinkansen line. | NTT docomo, Tokyo-area subway stations |
| NTT docomo's Kansai subway page lists Osaka Metro lines for the same station check. It is current as of 2026-06-30, says some places inside a station may be unusable, and does not name a Shinkansen line. | NTT docomo, Kansai subway stations |
| au's area page says you can check current and planned service-area maps by phone type, including 5G and LTE phones, and by prefecture. Region labels on the page include Hokkaido and Tohoku, and Kyushu and Okinawa. au says that after a map is published, moving base-station equipment can create spots outside the area with no notice. | au, service area |
| au's 4G LTE map for 1.7 GHz and 2.0 GHz is for phones that support those bands and do not support 800 MHz. au says to confirm the phone's frequencies with the business that released the phone. | au, service area |
| au says mountain-hut Wi-Fi, using Starlink, is for huts where radio is hard to reach, that the Wi-Fi now covers 100 places, that au names the 100 famous mountains as examples, and that au customers can use it. The same page says KDDI uses Starlink where a fiber line is hard to lay in mountainous areas and at outdoor events, and that KDDI builds area along railways and commercial districts. | au, service area |
| au's mountain-trail page lists trails and spots on the 100 famous mountains for 4G LTE phones that support 800 MHz. The page was updated on 2021-01-26. au says available and partly available are approximate results of au's own survey, that the map can change, that the season and snow can make a marked place hard to use or limit it to part of the year, that a spot which works only in part may still be marked available, and that the trail map and the service-area map can differ because one is a field survey and the other is calculated. | au, mountain trails |
| As of July 2026, au lists above-ground stations and the sections between them where it has done 5G work, on lines you select on that page. au says a place marked available can still be unusable, and that underground sections and underground station facilities may be unusable. au says 5G reaches indoors less readily than 4G LTE, so a place inside the mapped area may use 4G LTE instead. The page does not name a Shinkansen line. | au, 5G on rail lines |
| SoftBank publishes a service-area map. | SoftBank, service-area map |
| SoftBank says that inside a service area, maintenance can make some or all of the service unavailable, and that tunnels, underground places, the inside of buildings, mountainous areas, and places near a boundary may be unusable. SoftBank also says a call or a data session can drop while you are not moving, even when the signal bars are at their strongest. | SoftBank, service-area limits |
| au Starlink Direct is au's own service. au's service-area note, dated July 2026, places it outside au 5G and 4G LTE coverage in Japan, including territorial waters, the contiguous zone, and ferry routes. au says a compatible phone can use some apps' data there when the sky is visible, that voice calls are not supported, and that the surroundings can limit the connection. au names this for au customers, and also for UQ mobile and povo2.0. | au Starlink Direct |
FAQ
Which operators does a Japan eSIM use?
The plan page lists the operator names stored for the plan you open, and it does that per plan. This page does not give one operator list for every Japan plan.
Does it work in rural areas?
Check the coverage page for the operator named on that plan. NTT docomo's service-area page is a prefecture search for where docomo shows 5G and LTE, across 47 prefectures. au's area page is a check by phone type and prefecture, and au says a published map can later have spots outside the area, with no notice, when base-station equipment moves. SoftBank says that inside a service area, mountainous areas and places near a boundary may be unusable. None of those pages says every rural place has service.
Does it work in the mountains?
NTT docomo's trail search shows approximate spots and says radio conditions can make use difficult. The result date on that search is 2025-09-02. au's list for the 100 famous mountains is for 4G LTE phones that support 800 MHz, was updated on 2021-01-26, and au says a place marked available can still be hard to use because of the season or snow. au's mountain-hut Wi-Fi is for au customers. au's area page also says KDDI uses Starlink where fiber is hard to lay in mountainous areas.
Does it work in Okinawa, Hokkaido, or on other islands?
NTT docomo's prefecture search includes Hokkaido and Okinawa. au's area page includes the regions Hokkaido and Tohoku, and Kyushu and Okinawa, and says to check by prefecture. Those pages do not say every part of either prefecture has service. au Starlink Direct is a separate au service, for au customers and for the UQ mobile and povo2.0 plans au names. au's July 2026 note places it outside au 5G and 4G LTE coverage, including territorial waters and ferry routes, and says voice calls are not supported.
Does it work on trains and in the subway?
NTT docomo's subway pages, current as of 2026-06-30, list lines in the Tokyo area and on Osaka Metro where you can check stations for 5G and LTE, and say some places inside a station may be unusable. au's July 2026 list is above-ground stations and the sections between them on named lines, and au says underground sections may be unusable. SoftBank says tunnels and underground places may be unusable inside a service area.
Does it work on the Shinkansen?
NTT docomo's subway pages dated 2026-06-30, and au's July 2026 rail list, do not name a Shinkansen line. Those pages are not a Shinkansen coverage map.
Does 5G work outside a major city?
The plan page shows the network type stored for that plan. This page does not restate it. NTT docomo's service-area page is where you check whether docomo shows 5G or LTE at a place. au says that inside a mapped area, indoor use may be 4G LTE rather than 5G, because 5G reaches indoors less readily.
Sources
Wakamo Japan plan pagewakamo.io
Wakamo product information. Wakamo keeps an operator name and a network type on a plan only when both are present. The plan page's Network line shows the network type stored for that plan, and the operator names stored for that plan when it has any. With no generation stored, the line says Network type not specified.
Accessed 2026-10-20.
NTT docomo, service areadocomo.ne.jp
docomo says you can check where 5G and LTE service is available. The prefecture search on that page lists 47 prefectures, including Hokkaido and Okinawa.
Accessed 2026-10-20.
NTT docomo, mountain trailsdocomo.ne.jp
docomo publishes a search of mountain trails where a phone can be used. The spots are approximate, and radio conditions can make use difficult. The search result is dated 2025-09-02, when the Hakusan map was updated.
Accessed 2026-10-20.
NTT docomo, Tokyo-area subway stationsdocomo.ne.jp
docomo lists Tokyo Metro, Toei Subway, Yokohama Municipal Subway, and the Minatomirai Line so you can check stations for 5G and LTE. The page is current as of 2026-06-30, says some places inside a station may be unusable, and points to the service-area map. It does not name a Shinkansen line.
Accessed 2026-10-20.
NTT docomo, Kansai subway stationsdocomo.ne.jp
docomo lists Osaka Metro lines for the same station check. The page is current as of 2026-06-30, says some places inside a station may be unusable, and does not name a Shinkansen line.
Accessed 2026-10-20.
au, service areaau.com
au says you can check current and planned maps by phone type, including 5G and LTE phones, and by prefecture. Region labels include Hokkaido and Tohoku, and Kyushu and Okinawa. After a map is published, base-station moves can create spots outside the area with no notice. The 1.7 GHz and 2.0 GHz LTE map is for phones on those bands that do not support 800 MHz. Hut Wi-Fi using Starlink is for huts where radio is hard to reach. au says that Wi-Fi now covers 100 places, names the 100 famous mountains as examples, and is for au customers. The page says KDDI uses Starlink where fiber is hard to lay in mountainous areas and at outdoor events, and builds area along railways and commercial districts.
Accessed 2026-10-20.
au, mountain trailsau.com
au lists trails and spots on the 100 famous mountains for 4G LTE phones that support 800 MHz, updated 2021-01-26. Available and partly available are approximate, from au's own survey. The map can change. Season and snow can make a marked place hard to use, and some service is seasonal. A spot that works only in part may still be marked available. The trail map is a field survey and the service-area map is calculated, so they can differ.
Accessed 2026-10-20.
au, 5G on rail linesau.com
As of July 2026, au lists above-ground stations and the sections between them where it has done 5G work, on lines you select on that page. A place marked available can still be unusable, and underground sections and underground station facilities may be unusable. Inside a mapped area, 5G may give way to 4G LTE because 5G reaches indoors less readily. The page does not name a Shinkansen line.
Accessed 2026-10-20.
SoftBank, service-area mapsoftbank.jp
SoftBank publishes its service-area map at this page.
Accessed 2026-10-20.
SoftBank, service-area limitssoftbank.jp
SoftBank says that inside a service area, maintenance can make some or all of the service unavailable, and that tunnels, underground places, the inside of buildings, mountainous areas, and places near a boundary may be unusable. A call or a data session can also drop while you are not moving, even when the signal bars are full.
Accessed 2026-10-20.
au Starlink Directau.com
au Starlink Direct is au's own service. au's July 2026 service-area note places it outside au 5G and 4G LTE coverage in Japan, including territorial waters, the contiguous zone, and ferry routes. A compatible phone can use some apps' data when the sky is visible. Voice calls are not supported. Surroundings can limit the connection. au names au customers, and also UQ mobile and povo2.0.
Accessed 2026-10-20.