Search “Japan unlimited eSIM” and you’ll see the same paradox:
Some travelers say it’s blazing; others feel throttled—because “unlimited” is not one specification.
This guide separates two Jeko AU (KDDI) options: true uncapped vs ~10 Mbps fair-use unlimited—so you can match the plan to your trip—plus a note from our own field speed tests.
(Usage estimates: how much data. Carriers: Docomo / SoftBank / KDDI. Catalog: Japan eSIM.)
Bottom line
- Typical sightseeing → AU KDDI ~10 Mbps unlimited
- Heavy hotspot / long video calls / live high-quality uploads → AU KDDI true uncapped
- Both are Japan-native network + Japan IP; the difference is speed policy
Two “unlimited” meanings
| Jeko name | How to read the policy | Product |
|---|---|---|
| True uncapped | Not intentionally locked to ~10 Mbps; real speed still varies by place/congestion; field-tested ~600 Mbps in central Fukuoka (reference only) | No-limit / true uncapped |
| ~10 Mbps unlimited | Fair-use unlimited around 10 Mbps; speed tests often ~7–12 Mbps | Unlimited (10 Mbps) |
Field note: how fast is true uncapped?
True uncapped isn’t only “not locked at 10 Mbps”—in strong urban signal, the feel is very different from a ~10 Mbps plan.
- Central Fukuoka: our own tests reached about 600 Mbps
- Commercial areas: often around 100–200 Mbps
- Slower spots: airports, hotel interiors, shaded signal, crowded hours
Speed varies by device, time, and cell load. Treat these as field references, not a promise for every traveler—always follow the live product page.
Comparison table
| Factor | True uncapped | ~10 Mbps unlimited |
|---|---|---|
| Carrier / IP | AU (KDDI) · Japan IP | AU (KDDI) · Japan IP |
| Maps / chat | Usually very comfortable | Usually enough |
| 720p video | More headroom | Often OK |
| Heavy hotspot / 1080p / long calls | Better fit | May stutter |
| Value | Experience-first | Best for most trips |
When to choose true uncapped
- Laptop/tablet hotspot for work or streaming
- Lots of original photo/video uploads while moving
- Long video meetings where stability matters
When ~10 Mbps is enough
- City maps, transit, LINE as the core
- Uploads mostly on hotel Wi‑Fi
- Short-form video is occasional, not hours on the go
Myths
- “Unlimited = peak speed-test forever.” No—true uncapped removes a 10 Mbps lock, not physics or congestion.
- “10 Mbps can’t run maps.” Typical travel use is fine; pain points are hotspot and heavy uploads.
Pre-purchase checklist
- Do you need heavy hotspot / long video?
- Confirm which AU KDDI SKU you’re buying
- Read days, APN, activation, hotspot notes
- Install before departure; enable data in Japan (setup)
- Keep home SIM for OTP
Always follow the live product page. This article is a buying guide, not a speed guarantee.
Once you know true uncapped vs ~10 Mbps unlimited, open Jeko Japan eSIM and match the plan to your trip—so you look at Japan, not your data meter.
