Japan Unlimited eSIM With No Throttling: KDDI 5G, Japan IP (2026)
A Japan eSIM with no daily cap and no slowdown, on KDDI/au 5G with a Japan IP: $19.03 for 3 days to $62.01 for 15, from $4.13 a day. Checked 3 Nov 2026.
Short answer: ONE eSIM's Special pack for Japan is unlimited data with no daily cap and no slowdown, on KDDI/au with 5G and a Japan IP address. It costs $19.03 for 3 days, $25.93 for 5, $33.28 for 7, $44.47 for 10 and $62.01 for 15, from $4.13 a day. The days start when you buy, and it cannot be topped up. Prices checked 3 November 2026.
Most "unlimited" travel eSIMs give you a set amount of full-speed data each day, then slow you to a fair-use speed until midnight. That is fine for maps and messages, and frustrating on a day of video calls or uploads. These Japan plans work differently: there is no daily allowance to use up, so the speed you get at 9 pm is the speed you got at 9 am.
What you get
- No daily cap and no fair-use slowdown. The plan page lists 999 GB: that is a technical ceiling set on the plan, not a daily allowance, and far beyond what one phone uses in 15 days.
- KDDI/au, one of Japan’s three big networks, with 5G where it is available and 4G or 3G elsewhere.
- A Japan IP address: the connection exits in Japan, so Japanese sites, streaming and banking apps see you as being in Japan.
- Data only, like every ONE eSIM plan: keep your home SIM for calls and texts.
- Find it on the Japan page, in the Special tab, each plan marked Special pack.
Prices
| Days | Price | Per day |
|---|---|---|
| 3 days | $19.03 | $6.34 |
| 5 days | $25.93 | $5.19 |
| 7 days | $33.28 | $4.75 |
| 10 days | $44.47 | $4.45 |
| 15 days | $62.01 | $4.13 |
Against our daily plans for Japan
| Plan | 7 days | What you get each day |
|---|---|---|
| No-throttling unlimited (KDDI/au) | $33.28 | No cap and no slowdown, Japan IP |
| 2 GB a day | $30.80 | 2 GB at full speed, then 1 Mbps |
| 5 GB a day | $84.70 | 5 GB at full speed, then 384 Kbps |
| 10 GB a day | $96.25 | 10 GB at full speed, then 384 Kbps |
Up to about 2 GB a day, a daily plan costs about the same or less and runs on all four Japanese networks. Above that, the no-throttling plan is far cheaper: a week of 5 GB a day costs more than twice as much, and still slows down once the 5 GB is used.
Against other providers
In our Japan price comparison of five providers (prices read on 4 November 2026), Holafly’s 7-day Japan plan has no daily cap either and costs less, at $27.50, though it says fair use may slow very heavy use. Airalo, Saily and Nomad give 2 to 5 GB a day at full speed, then 1 Mbps, for $25.00 to $26.99 a week. Pick this plan for KDDI 5G with a Japan IP and no slowdown at all; pick a daily plan if you use a few gigabytes a day or less.
Two things to know before you buy
- The days start when you buy, not when you first connect in Japan as on most of our plans. Buy it on the day you land, or the evening before, and install it straight away.
- It cannot be topped up. Pick the length that covers the whole stay; if you stay longer, buy a second plan for the extra days.
Who it suits
- Working from Japan: video calls, uploads and remote desktops all day.
- Streaming and posting video while you travel.
- Anyone who does not want to count gigabytes or watch the speed drop in the evening.
FAQ: Japan eSIM with no throttling
- Is it really unlimited? Yes for practical purposes: the plan has no daily cap and no fair-use slowdown. It carries a 999 GB technical ceiling, which one phone will not reach in 15 days.
- Which network does it use? KDDI/au, one of Japan’s three big networks, with 5G where it is available.
- Will Japanese apps and sites work? Yes. The internet exits in Japan, so sites and apps see a Japan IP address.
- When do the days start? When you buy the plan, not when you land. Buy it on arrival day or the evening before.
- Can I top it up? No. Choose the number of days that covers your trip, or buy a second plan later.
- Does it come with a Japanese phone number? No, it is data only. Calls and texts stay on your home SIM, or use LINE, WhatsApp or FaceTime over the data.