Set up your Japan eSIM before you fly, and pick one that runs on Docomo or Au if your trip leaves Tokyo or Osaka. Japan has no SIM registration or passport requirement for tourist eSIMs, which makes it one of the simplest countries in the world to get connected in, but the network your eSIM uses still determines whether it works well on rural train lines or mountain routes. This guide covers how eSIMs work in Japan, which network to choose, and how much data you actually need.
Why Your Belgian Plan Doesn't Just Work in Japan
Japan is far outside the EU roaming zone, so your Belgian operator bills it as a standard non-EU destination. Check your provider's app before you fly. Without a Japan-specific pass, expect per-day or per-MB roaming charges that add up quickly over a multi-week trip, which is common for Japan visits.
Setting Up an eSIM in Japan Is Refreshingly Simple
Unlike Turkey or Morocco, Japan has no passport registration, no IMEI check, and no local ID requirement for a tourist eSIM. You buy, install, and activate, and that's the whole process. This is one of the easiest countries in the world for eSIM setup, and it's worth knowing in advance so you don't waste time hunting for paperwork you don't actually need.
How Much Data Do Light Users Actually Need?
| Activity | Typical Data Use |
| Google Maps Navigation (1 hour) | 5-10 MB |
| WhatsApp texts + a few photos (per day) | 10-20 MB |
| Digital Boarding Pass or Hotel Confirmation | Under 1MB |
| Ride hailing app (per booking) | 5-10 MB |
| Light Browsing or Email (30 minutes) | 15-25 MB |
Add it up and a light-use day in Japan, maps around Tokyo, messaging, a train lookup, some browsing, usually lands between 60 and 120 MB. Even a two-week trip of light use rarely clears 2 GB. A modest eSIM bundle covers this comfortably and works out far cheaper than non-EU roaming rates.
If your travel days look like this, a small eSIM bundle is often all you need. Instead of paying non-EU roaming rates by the day, a 1GB Firsty eSIM covers maps, messages, boarding passes and the occasional ride booking with room to spare.
Check our plans and set it up before you land, so you're connected from the moment you touch down.
eSIM vs Pocket WiFi in Japan
Pocket WiFi rental counters are a fixture at every Japanese airport, and for good reason: it's historically been a popular option here. But for solo travellers and couples, an eSIM is now generally the better choice. It's cheaper, needs no extra device to carry or charge, has no deposit to worry about, and keeps working underground on the subway where a pocket WiFi router can sometimes drop signal. Pocket WiFi still makes sense for groups of three or more sharing a single connection, since it splits the cost across more people and devices.
What to Check Before You Book a Japan eSIM
Confirm which network the eSIM actually runs on using the table above, since it's the single biggest factor in how well it performs outside the main cities. Match your data allowance to your route with the usage table above rather than guessing. Check the price is stated clearly upfront, and confirm whether the plan includes calls and texts or is data only, since most Japan travel plans are data-only.
Where Firsty Fits In
Check whether your Firsty plan already covers Japan before you fly, since it sits far outside the EU roaming zone and isn't included by default the way EU countries are. If it isn't, a Japan eSIM works the same way as any other Firsty plan: no zone chart to check, no roaming toggle to flip, and no surprise bill once you're home. Check current plans, pricing, and network coverage for Japan.
FAQ
Do I need an eSIM for Japan? Not strictly, but it's usually the cheapest and simplest option. Without one, you're relying on your Belgian roaming rate, billed at non-EU rates for the length of your trip.
What is the best eSIM for Japan? It depends on your route. For Tokyo, Osaka, and Kyoto, most eSIMs work well. For rural areas or mountain routes, choose one that includes Docomo or au.
Does my Belgian phone plan cover Japan? Not automatically. Japan is far outside the EU roaming zone, so check your operator's app for a Japan-specific pass before you travel.
Is an eSIM better than pocket WiFi in Japan? For solo travellers or couples, usually yes: cheaper, no device to carry, and no deposit. Pocket WiFi still suits groups of three or more sharing one connection.
Do I need to register my eSIM in Japan? No. Japan has no passport, ID, or IMEI registration requirement for tourist eSIMs, making it one of the simplest countries to set up in.
