The best eSIM for Japan

Japan is one of the easiest places in the world to use a travel eSIM. Coverage is excellent almost everywhere a visitor goes, including the shinkansen and most of the metro network, and every major provider sells a Japan plan. The choice is not about coverage. It is about what "unlimited" means, and whether you need to make phone calls.

Unlimited in Japan usually means a daily allowance

Nearly every provider selling an "unlimited" Japan eSIM caps your full-speed data per day and then slows you down until midnight. The allowances differ by more than most people realise:

• Airalo gives 3GB a day, then 1Mbps.
• Saily gives 5GB a day, then 1Mbps.
• Nomad gives 2GB a day, then 512kbps.
• Ubigi works differently again: it caps the whole plan rather than the day, and its Japan plans do not all use the same figure.
• Holafly publishes no figure at all. Their terms say only that speed may be subject to a fair use policy.

A 3GB daily allowance is a lot for maps, messaging and a few hours of scrolling. It is not a lot if you are working from a laptop or streaming. And 1Mbps still loads maps and WhatsApp, so a throttled plan is far from useless, but it will not stream video.

This is why the table on this site scores a capped plan on what it actually gives you at full speed rather than on price per day. A 30-day plan with a 3GB daily cap is a 90GB plan, and it should be compared with one.

Travel eSIMs in Japan do not make phone calls

Almost every travel eSIM sold for Japan is data-only. You get internet, so WhatsApp, FaceTime, Signal and Google Voice all work, but you have no Japanese number and you cannot dial an ordinary phone number.

That matters more in Japan than in most places, because restaurant bookings, ryokan check-ins and taxi firms still expect a phone call, and some booking sites will not accept a foreign mobile number. If you know you need to ring people, either keep your home SIM active for outgoing calls or look at a plan that includes real cellular voice.

What to check before you buy

• Tethering. If you are travelling with a laptop or sharing with someone, check the plan allows hotspot use and whether it is capped. Some providers limit sharing to a small daily amount even on an unlimited plan.
• Which network it uses. Japan's networks are NTT Docomo, SoftBank, KDDI au and Rakuten. Coverage differences barely matter in cities and can matter in the mountains.
• Install before you fly. Install the profile at home over Wi-Fi. Most plans start counting when the eSIM first connects to a network in Japan, not when you install it, but check that on the provider's page rather than assuming.

Compare the current Japan plans, or read the install guide first.