Japan eSIM for Tokyo, Kyoto, the Shinkansen, and the mountains

Japan runs on a transit card in your phone's wallet, a Shinkansen ticket bought in an app, and a translation camera pointed at a menu, and all three need data from the moment you clear immigration at Narita or Haneda. The best eSIM for Japan is the one added at home, on Wi-Fi, so the Suica is loaded and the airport train is tapped through before the bags come round.

Below: how a Japan plan works, how to set it up before you fly, what to expect in Tokyo and Kyoto, on the trains, and in the mountains and islands, and which plan fits when South Korea or Taiwan is on the same trip.

Asian trips tend to be multi-stop, and most travel eSIMs want a fresh profile at every airport. KnowRoaming doesn't. You add the KnowRoaming eSIM, called KR.One, to your phone once, then add a plan per trip: one country for a single-city break, the Asia plan when the route runs through several, and next year's trip on the same eSIM. Nothing to scan again, nothing to delete when you get home.

The plan's days start when you turn it on and connect in Japan, not at checkout. Buy it weeks ahead, add it at home, and a delayed flight costs you nothing. The full rule is in what plan validity means and when it starts.

Choose a fixed plan for a set amount of data at the lowest overall price, or an unlimited plan when you'd rather not count. Unlimited plans give you 5 GB a day at full speed, then a slower speed until the allowance resets the next day. If a fixed plan runs low, top up in the app and the extra data lands on the same eSIM.

See it in two minutes: Meet KR.One, iPhone setup with KR.One, or Samsung setup with KR.One.

Do this at home on Wi-Fi. It takes about a minute.

Before you leave

1. Get the KnowRoaming app (available on iOS and Android) and choose your Japan plan.
2. Tap Add. First time on this phone? The app adds KR.One and your Japan plan together. Already have KR.One? Only the plan is added, with nothing to scan.
3. Leave data roaming off on the KnowRoaming line until you land, and turn it off on your home line too so it doesn't run up charges in the background. Steps are in turning off roaming on your home line.

When you land

1. Turn the plan on in the app, then turn data roaming on for the KnowRoaming line. That setting lives in your phone, so the app can't flip it for you.
2. Give the phone a minute to find the network. If nothing happens, turn airplane mode on for 30 seconds and off again.

Prefer a QR code? The checkout page and your confirmation email both carry one; scan it from your phone's settings. Every tap, by device, is in adding your eSIM on iPhone, adding your eSIM on Android, and adding your eSIM on Samsung, or watch the iPhone QR walkthrough or the Samsung QR walkthrough. Still no signal after landing? Work through the no-signal checklist.

Narita is an hour from central Tokyo by the Narita Express or the Skyliner; Haneda is about half an hour by monorail or Keikyu line. A Suica or PASMO card loads into Apple Wallet or the Android equivalent and pays for every train, bus, and convenience store in the country; the physical Welcome Suica is the fallback. GO is the taxi app, and Uber works through licensed taxis in the big cities.

The yen is the currency, cards and phone wallets are accepted far more widely than they were, and cash still matters at shrines, small restaurants, and the countryside; the 7-Eleven ATMs take foreign cards. Tax-free shopping needs the passport at the till.

Tokyo itself is a week: Shibuya and Shinjuku, Asakusa and the Skytree, Tsukiji's outer market, the teamLab museums with timed tickets that sell out weeks ahead, and the day trips to Kamakura, Nikko, and Hakone by train. The city's rail map is the reason the Suica lives in the phone.

Tokyo to Kyoto is two hours and a quarter by Shinkansen, Kyoto to Hiroshima under two, with seats booked in the SmartEX app or at the machines and 5G along most of the lines; the JR Pass is worth the math since its price rose, and often isn't. Kyoto's temples, Nara's deer, Osaka's food, and Hiroshima's peace park are the classic fortnight, and the popular temples and museums sell timed tickets online.

The Japanese Alps around Takayama and Kamikochi, the Kumano Kodo pilgrimage trails, and the Fuji climbing season in July and August are the mountains, with 5G in the towns and drops on the trails and the high huts. Hokkaido's Niseko and Furano are the powder, a flight or the Shinkansen to Hakodate; Okinawa's islands are the beaches, covered by the Japan plan with 4G on the main island and thinner coverage on the outer ones.

Golden Week at the end of April and the start of May, Obon in mid-August, and the New Year fill every train and hotel; the cherry blossom in late March and early April and the autumn colors in November are the crowded weeks worth crowding for. Book the Shinkansen seats and the ryokans ahead on the phone for any of them.

Japan is on the Asia plan, 28 countries on one plan that also covers South Korea, Taiwan, Hong Kong, and Southeast Asia, switching networks by itself when you land; a Tokyo and Seoul trip or a Taipei stopover fits it without any change in the app. Japan is also on the Global plan. A Japan-only plan stops at the coast. Read do I need a new plan for every country? for the detail.

Your plan connects to KDDI or Rakuten, with 5G in Tokyo, Osaka, Kyoto, Nagoya, Fukuoka, Sapporo, and every regional city and along the Shinkansen corridors, and 4G LTE across the towns, the coasts, and Okinawa. KDDI's footprint is the wider of the two, and the phone prefers whichever is stronger; there is nothing to choose by hand.

In the Alps above the trailheads, on the Kumano Kodo's remoter stages, and on the outer Okinawan islands, expect gaps on any network. Save what you need in town.

Most phones sold since 2019 support eSIM, including iPhone XS and later and most Android flagships from the same window. Check yours before you add a plan; it takes a few seconds. On iPhone, go to Settings, General, About and look for an EID or Available SIM. On Android, go to Settings, Network & Internet, SIMs and look for an option to add an eSIM. On Samsung, dial *#06# and look for an EID.

Your phone also needs to be carrier-unlocked. If you're not sure, carrier-locked vs unlocked: how to tell shows you where to look.

Adding a Japan plan doesn't touch your regular SIM. Calls and texts on your usual number keep working exactly as before. The new plan handles data while you're there, and most phones run both at once without you doing anything else. Bank codes and two-factor texts still arrive on your home number, as long as that line stays switched on.

For Asia the alternatives are a home-carrier roaming pass that resets at every border, an airport SIM counter at each arrival, or hotel Wi-Fi that stops at the lobby. A Japan plan added at home beats all three: one price agreed before you fly, live the second you land, and one plan across every stop on the route.

Real travelers rate KnowRoaming 4.5 out of 5 on Reviews.io. More than a decade in travel connectivity, more than 200 destinations, and support that doesn't clock off: WhatsApp and live chat, any time, any day.

One plan. No roaming surprises. Live the moment you land.

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4.5 out of 5 on Reviews.io. 200+ destinations. Support that doesn't clock off.