SIM Cards and Internet in Japan: Staying Connected When You Can't Read a Word of Japanese on the Road

In a Japanese rental car, the built-in navigation screen usually displays its menus in Japanese only, and directional signs rarely offer anything but kanji characters once you leave the expressway. The habit that quickly takes hold: mount your own smartphone and let Google Maps or the Japanese app NAVITIME handle the guidance, typing in the phone number of a destination rather than its address when needed — a trick rental companies themselves recommend, since Japanese addresses stay largely unreadable to a Western system.

This reliance on mobile GPS has a documented downside. A study by Toru Ishikawa, Hiromichi Fujiwara, Osamu Imai and Atsuyuki Okabe, published in 2008 in the Journal of Environmental Psychology, compared pedestrians guided by GPS with those using a paper map or simply walking the route once beforehand: GPS users travelled longer distances, stopped more often to check the screen, and afterwards retained a noticeably less accurate mental map of the route they had just walked (study available on Google Scholar: scholar.google.com/scholar?q=Ishikawa+Fujiwara+Imai+Okabe+2008+Wayfinding+GPS-based+mobile+navigation+system). On Japan's narrow mountain roads, where a missed turn can send you straight onto a one-way lane, glancing at the overall route before setting off remains a good habit — without doing away with a reliable connection for the rest of the drive.

France's four carriers treat Japan very unevenly. Since late March 2026, Free has offered its Free Max plan, which includes unlimited data in 121 destinations including Japan, for €29.99/month (€19.99 for Freebox subscribers) with no commitment — the simplest option for anyone already with Free. Orange doesn't cover Japan under its standard plans: you need to add a Pass Voyage 1 (around €30 for 31 days) or subscribe to its Voyage 250 Go 5G plan, which includes an allowance usable outside Europe. RED by SFR includes Japan in its B&You 250 Go Voyage plan (roughly €16/month, 40 Go usable across more than 110 destinations). Bouygues Telecom bundles Japan into most of its more generous 5G plans (150 to 300 Go), with an on-the-ground allowance of 35 to 40 Go depending on the plan, or a one-off Pass Confort around €35 for 10 Go.

As usual, it's worth checking your plan's exact terms before departure rather than discovering them at the rental counter: allowances and covered destinations change frequently from one year to the next.

Unlike many countries, Japan doesn't readily sell SIM cards with a phone number and calls to visiting tourists — that option is in practice reserved for residents. Counters and vending machines at Narita, Haneda and Kansai airports do sell data-only SIM cards instead, on the Docomo or SoftBank networks: expect ¥2,000 to ¥3,000 for around 5 Go over 7 to 10 days, and ¥4,000 to ¥6,000 for larger or unlimited plans over 15 to 30 days. bmobile, Sakura Mobile, eConnect and IIJmio run stands at all three airports as well as at the big electronics chains Bic Camera and Yodobashi Camera in town; a passport is all you need.

With no number to call or be called on, this card stays geared towards navigation and online bookings — plenty for a road trip, as long as you have another way to reach your rental company or accommodation if needed (michi-no-eki wifi, a messaging app).

To land already connected, a tourist eSIM activates from an app before you even board. Airalo offers Japan plans starting around $5 for 1 Go over 7 days, up to roughly €20 for 20 Go over a month; Ubigi and Holafly focus on unlimited-data plans, between $5 and $9 a day depending on the length of stay. Sakura Mobile, a specialist in the Japanese market, sells its own eSIMs on the Docomo network — the country's widest, including in rural and mountain areas — with English-language support that helps if something goes wrong.

This kind of eSIM mainly secures the airport-to-rental-counter leg and the first hours on the ground; after that, nothing stops you switching to a local prepaid SIM or a pocket wifi if the plan doesn't cover the whole trip.

Japan has a feature few other self-drive destinations offer: the pocket wifi router, booked in advance and picked up at the airport counter or delivered straight to your hotel by post. Ninja WiFi, Japan Wireless and Sakura Mobile charge roughly $5 to $9 a day for these routers, offering an unlimited connection shared across several devices — enough to connect the driver, passengers and a tablet for the kids on the long hauls across Hokkaido or Kyushu. Returning it usually means slipping the unit into a prepaid envelope and dropping it in any Japanese postbox, or handing it back at the departure airport counter.

The appeal of a pocket wifi fades quickly for a solo traveller with a recent eSIM-compatible phone — but it remains the best option for a group, a family, or an older phone that doesn't support eSIM.

Japan remains one of the best-covered countries on earth, far ahead of most self-drive destinations on this site — but coverage isn't uniform. Docomo, the country's oldest carrier, keeps the densest network in rural and mountainous areas and stays the safest choice for a road trip that strays from the main routes; SoftBank, very strong in cities, loses ground fast once you leave built-up areas.

The real coverage gaps are limited to a handful of well-identified pockets: peaks above 2,500 m in the Japanese Alps, around Mount Hotaka near Kamikochi or the Tateyama-Kurobe range, remote valleys in eastern Hokkaido such as Shiretoko or Lake Akan-Mashu, and the many mountain tunnels that cut the signal for the length of the crossing, regardless of carrier. On those stretches, maps downloaded offline before setting off (Google Maps, Maps.me) remain the best safety net.

Since the December 2019 revision of the Road Traffic Act, holding a phone while driving — to talk, read a message or check the GPS — carries a markedly heavier fine and points penalty, and can mean up to six months in prison or a ¥100,000 fine if it causes an accident. The rule applies just as much to residents as to a foreign driver carrying a JAF translation of their licence.

A dashboard mount and voice guidance instead of a handheld screen let you enjoy the GPS while staying within the law — and echo the warning from the Ishikawa study cited above: better to glance at the route before setting off than to navigate with your eyes glued to the screen once you're on a narrow mountain road.

A few things worth checking before hitting the road:

Staying connected is only one piece of preparing a self-drive road trip through Japan: the JAF translation of your driving licence, rental insurance and the NOC fee trap, tolls and the ETC card, and how many days to plan for stringing together the Japanese Alps, Hokkaido and Kyushu all deserve just as much thought before you set off.