The best eSIM for Japan, and how to choose yours

Start from what you actually do on your phone on a typical travel day. As a rough weekly guide:

• Light use (1–2 GB a week): maps, WhatsApp or LINE, email, train times and the odd search. Plenty if you save the heavy stuff for hotel Wi-Fi.
• Moderate use (3–5 GB a week): all of the above plus social media with photos and stories, camera translation, the occasional short video call and transport apps.
• Heavy use (10 GB a week or more): streaming video, daily video calls, uploading clips or sharing your connection with a laptop or a travel companion.

Free Wi-Fi exists in stations, convenience stores and some museums, but it often requires registration and it does not follow you down the street. If you are torn between two sizes, the larger one usually works out better per GB than running short and topping up halfway through the trip.

Total-data plans give you a pool of gigabytes for a set period: for Japan, 0.5–50 GB with validity of 1–30 days. You use it at your own pace, so a quiet hiking day in Hakone leaves more for the Tokyo day when you post everything.

Daily plans give you a high-speed allowance every day. Once you use it up, you stay connected at a reduced speed (fine for messaging, not for video) until the next day begins. They suit travellers who would rather not count megabytes and whose usage is similar from day to day. If your usage is uneven, a total-data plan is normally the more efficient choice.

Startia's standard Japan plans connect to the country's major networks: NTT docomo, KDDI/au, SoftBank and Rakuten Mobile, with 5G on most plans where your phone and the area support it. The exact networks depend on the plan and are shown on each plan's details.

In cities and along the main tourist routes, 4G and 5G coverage is dense, including much of the underground. In remote mountain areas or very rural spots there can be gaps, as anywhere. If you are heading for the Kumano Kodo trails or the Japanese Alps, download offline maps before you set off.

This is where Japan eSIMs differ most, and it is rarely explained:

• Basic plans. Depending on the plan, they either use standard routing, where your traffic reaches the internet through a regional hub such as Hong Kong, or IIJ, a Japanese provider running on the NTT docomo network that goes online with a Japanese IP address.
• Premium plans. These include KDDI-based plans (KDDI/au network, Japanese IP and generous data for short stays of 3 to 15 days; they cannot be topped up) and plans that avoid Hong Kong and route through Singapore instead, on SoftBank and KDDI/au.

When does the IP matter? For fussy banking apps, streaming services with country-specific catalogues, or Japanese websites that block foreign IP addresses. For maps, messaging and general browsing you will hardly notice the difference.

• Suica and PASMO on your phone. On iPhone you can add Suica or PASMO to Apple Wallet and tap through ticket gates and pay at convenience stores; on Android it depends on the model. Topping them up in the app needs a connection, so having data at the station helps.
• Many services want a Japanese number. Some restaurant booking sites, taxi apps and sign-up forms ask for a local number to send an SMS code. A data-only eSIM does not come with a phone number, so use platforms that accept international numbers or ask your hotel to book. Keep your physical SIM active if you need texts from your bank.
• Install before you fly. Validity starts with the first connection to a network in Japan, not when you install. On arrival, switch on data roaming for the eSIM line (needed because it uses partner networks) and switch it off on your home SIM.
• Label the line. The profile shows up as "Carrier"; rename it "Startia" so you can tell your lines apart.
• Japan and Korea on one trip? The Japan and South Korea regional plan covers both, on SoftBank and KDDI/au in Japan and SK Telecom and LG U+ in Korea.

Look beyond the headline price:

• Price per GB. For total-data plans, divide price by gigabytes. Startia starts from €0.78/GB.
• Real validity. How many days you get and when the clock starts.
• Hotspot. If you plan to share your connection, check that tethering is allowed.
• Top-ups. Many Startia plans can be topped up from your account; the Premium KDDI plans cannot.
• Networks and IP. Which operators are used and whether you get a Japanese IP.
• Support. Which languages and which channels. Startia answers in English and Spanish at esim-contact@startia.es or via a ticket from your order.
• Refunds. With Startia, if you have not installed the eSIM, you get your money back.

The Japan page lists every plan, from €4.99 including VAT. For one or two weeks of moderate use, the 5 GB Japan plan is a sensible starting point; if you share your connection or upload a lot, look at the 10 GB plan. You can pay by card, Apple Pay, Google Pay or PayPal, and the QR code arrives by email and on your order page. On iPhone with iOS 17.4 or later you can install it with a single tap.

If you would like to weigh us against other brands, our comparisons with Airalo and Holafly show their public prices with the date and source, so you can decide on facts rather than impressions.

Do I need a compatible phone to use an eSIM in Japan?

Yes. It must support eSIM and be carrier-unlocked. Dial *#06#: if an EID number appears, your phone has eSIM.

Will I get a Japanese phone number?

No. The eSIM is data-only. WhatsApp, LINE and FaceTime work over data, but you will not receive texts on a Japanese number.

When does the plan's validity start?

On the first connection to a network in Japan. You can install it at home days before without using any validity.

What is the difference between a basic and a Premium plan?

The route to the internet and the networks. Some basic plans (IIJ) and the Premium KDDI plans go online with a Japanese IP; other basic plans route through a regional hub.

Can I top up if I run out of data?

On many plans, yes, from your customer account. The Premium KDDI plans cannot be topped up.