Unlimited-data eSIM for Japan
A truly unlimited eSIM doesn't exist. They all carry a fair use policy: past a certain daily usage the speed drops. The only thing that changes from brand to brand is whether they tell you the number or let you discover it in Kyoto. For Japan there's a pass with 1 GB a day at full speed that then keeps working at 1 Mbps, and both figures are published.
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Day five. You're in the queue at the Fushimi Inari temple trying to upload a video of the torii gates and the bar won't move. Four bars of coverage, 5G in the corner of the screen, and a spinning circle. You paid for unlimited data. And yet there you are, watching a circle.
What the fair use policy is
No operator can hand out infinite traffic, because the network is finite and shared by everyone connected to that mast. That's why the plans called unlimited carry a threshold: past a certain usage, almost always daily, the speed is reduced until the next day. It's called a fair use policy, or FUP, and it's in the fine print across the whole industry.
The threshold always exists. What changes from one brand to another is whether they publish it.
Before buying any “unlimited” plan, from anyone, look for three things on their site: after how many megabytes the speed drops, what speed you're left with, and whether data sharing is included or extra. If the three answers aren't written on their page, you already know plenty.
What you can do at 1 Mbps
Japan's day pass works like this: every day you get 1 GB at full speed and, when it runs out, you stay connected at 1 Mbps until the next morning, when another gigabyte arrives. No cut-off, no top-up to buy.
- Maps and finding your way round the Tokyo metro: no problem
- The camera translator, for reading a menu: no problem
- WhatsApp, voice notes and photos included
- Email, looking up trains, booking a restaurant
- Voice calls over the internet
- Low-quality video: doable, with patience
- High-quality video, or uploading a long video: no
Put another way: at 1 Mbps you're still a person with internet in Japan. It's not a cut-off; it's the second course.
| 1 GB-a-day pass | Price |
|---|---|
| 7 days | 10,90 € |
| 15 days | 20,90 € |
| 30 days | 40,90 € |
When it's right for you and when it isn't
If you're going to burn well over 1 GB every single day — you work from there, you livestream, you share data with three people — an unlimited plan from another brand may work out better for you, and saying so costs us nothing. What never makes sense is buying one without knowing where the cut-off sits. And if your usage is normal, the maths usually runs the other way: 4,90 € for 3 GB over fifteen days covers the whole trip for less than almost any one-week unlimited.
Is there any truly unlimited eSIM?
Not in the literal sense. Every brand applies a fair use policy because a mobile network's capacity is finite. What does exist are plans with very high thresholds and plans that don't publish theirs.
What speed are you left with past the limit?
On Japan's day pass, 1 Mbps until the next day. Enough for maps, messaging, email and browsing; not enough for high-quality video. Other brands throttle to different speeds and not all of them publish them.
Does sharing data draw from the same allowance?
Yes. When you act as a hotspot, whatever the other device uses comes out of your daily gigabyte. Worth keeping in mind if there are two of you and one is on a laptop.
Do I lose internet when I use up the day's gigabyte?
No. You stay connected at reduced speed until the next morning, when the allowance resets. Nothing to top up, no extra to buy.
Something off, or a price changed? Write to ayuda@zasesim.com and we'll fix it. Data when you land.