eSIM for Japan: how to stay online from the moment you land
Which networks you connect to, how much data you really need, and how to set up an eSIM for Japan before you leave home.
Japan is one of the easiest countries in the world to travel with a phone. Trains run on time, signs are often in English, and almost everything you need, from train routes to restaurant queues, lives in an app. The catch is that all of it assumes you are online.
An eSIM is the simplest way to get there. It is a SIM card with no plastic: you install it on your phone before you leave, and when the plane lands you already have data. No shop at the airport, no pocket Wi-Fi to collect and return.
This guide covers what you need to know to set one up.
Why an eSIM beats the alternatives
Most visitors to Japan end up choosing between three options.
Roaming with your home carrier. It works without doing anything, which is the whole appeal. It is also usually the most expensive choice by a wide margin, especially if you use maps and social media all day.
Pocket Wi-Fi. A small router you rent at the airport or receive at your hotel. It is fast and several people can share it, but it is one more device to charge every night, it has to stay with you to work, and it has to go back before your flight home.
A travel eSIM. Data goes straight to your phone, with nothing to carry, charge or return. You buy it online, install it in a couple of minutes, and your usual number stays active for calls and messages.
For most travellers, especially solo travellers and couples who each have their own phone, the eSIM is the one with the fewest things that can go wrong.
Which networks you connect to
Japan has four mobile networks: NTT docomo, KDDI (au), SoftBank and Rakuten Mobile. Coverage in cities and along the main train lines is excellent on all of them, and 5G is widespread in urban areas.
Wigoo's plans for Japan connect to these local networks, so you get the same signal Japanese users get. The plan page lists which operators each plan uses.
Does my phone support eSIM?
Most phones sold in the last few years do. On iPhone, every model from the iPhone XS and XR onwards supports eSIM. Recent Google Pixel and Samsung Galaxy phones do too.
The one thing to check is that your phone is unlocked, meaning it is not tied to a single carrier. If you bought it outright it almost certainly is. If it came with a contract, your carrier can tell you, and most will unlock it on request once the contract terms allow.
The Wigoo app checks compatibility before you pay, so you never buy a plan your phone cannot use.
How much data do you need?
It depends much more on how you use your phone than on how long you stay. As a rough guide:
- Maps, messages and email. Navigation and chat use very little. A few hundred megabytes a week is often enough, and 1 to 3 GB covers a short trip comfortably.
- Everyday use, with some social media. Posting photos, checking Instagram on the train, the odd video. Plan on 5 to 10 GB for one to two weeks.
- Heavy use. Video calls, streaming, sharing your connection with a laptop. Here an unlimited day pass makes more sense than a fixed amount.
Wigoo's Japan plans range from 1 GB for a week to 20 GB for a month, plus day passes that give you 2 GB a day at full speed and then keep you online at a lower speed until the next day. If you run short, you can top up the same eSIM from the app, without installing anything new.
Setting it up, step by step
- Buy the plan before you leave. Pick Japan, choose how much data you want, and pay in your own currency.
- Install it at home, on Wi-Fi. The installation needs a connection, so do it before you get to the airport, not after you land.
- Keep your usual line on. Your home SIM stays active for calls and texts, and you can still receive the codes your bank sends you by SMS.
- When you land, switch data to the Wigoo line. In your phone's settings, set the Wigoo eSIM as the line for mobile data and turn on data roaming for it. That is it: you are online.
Turning on roaming for the eSIM does not mean paying your home carrier for roaming. It only tells the phone that it is allowed to use a network outside the eSIM's home country. To avoid surprises, keep data roaming off on your usual line.
A few things worth knowing about Japan
- Your eSIM is data only. You will not get a Japanese phone number. For calls, WhatsApp, LINE and FaceTime work over data, and LINE is the app most people in Japan use.
- Add a transit card to your phone. On iPhone you can add a Suica or PASMO card to Apple Wallet and tap through ticket gates without buying paper tickets. Topping it up needs a connection, which is one more reason to have data from day one.
- Free Wi-Fi exists, but do not rely on it. Stations, airports and many convenience stores offer it, but it often asks for registration and it disappears the moment you walk away.
- Download offline maps anyway. Even with a good plan, a downloaded map of the city you are visiting is a useful safety net in the subway and in the mountains.
Quick answers
Can I install the eSIM before I travel?
Yes, and you should. Install it at home on Wi-Fi, then switch mobile data to it when you arrive.
Will I keep my WhatsApp and my number?
Yes. WhatsApp is tied to your number, not to your SIM, and your usual line stays active next to the eSIM.
What if I run out of data?
Top up from the app. The same eSIM keeps working, so you never need to reinstall anything while you are away.
Does it work outside the big cities?
Japan's networks cover the vast majority of the populated country, including most rural towns and the main tourist routes. Remote mountain areas can still have gaps, as they do everywhere.