TL;DR
NTT Docomo and SoftBank are Japan's two largest mobile carriers, but they're not equal. Docomo covers 99% of Japan's territory — including most rural areas and Shinkansen tunnels — compared to roughly 96% for SoftBank. For travelers, Docomo is the safer choice. It's the network used by PlanJapan eSIMs.
Docomo vs SoftBank: Quick Comparison
| Criteria | NTT Docomo | SoftBank |
|---|---|---|
| Population coverage | ~99% | ~96% |
| Rural coverage | Excellent | Good (towns and cities) |
| Shinkansen (tunnels) | Very good | Decent |
| 4G LTE speed (urban) | 50–150 Mbps | 50–130 Mbps |
| 5G available | Yes (major cities) | Yes (major cities) |
| Used by PlanJapan | ✅ Yes | ❌ No |
Coverage: Why Docomo Leads
NTT Docomo is Japan's incumbent carrier — the equivalent of AT&T or T-Mobile in terms of legacy infrastructure. Decades of investment mean its network extends far beyond major cities:
- Tokyo, Osaka, Kyoto, Sapporo: Full 4G/5G coverage, excellent speeds
- Rural areas (Tohoku, Japanese Alps, inland Shikoku): Stable signal where SoftBank can become unreliable
- Islands (Okinawa, Hokkaido, Kyushu): Docomo covers the vast majority of populated areas
SoftBank delivers excellent coverage in urban and suburban areas. If your trip stays within Tokyo, Kyoto, and Osaka, both networks are comparable. But the moment you head off the beaten path — hiking remote mountains, visiting historical villages, soaking in secluded onsen — Docomo's advantage becomes clear.
Shinkansen Performance
The Shinkansen crosses dozens of tunnels, especially on the Tokaido (Tokyo–Osaka) and Sanyo lines. Docomo has invested heavily in tunnel infrastructure, with repeaters installed throughout most major line tunnels.
In practice: with a Docomo eSIM, you can work, stream, or use Maps for virtually the entire Tokyo–Kyoto journey. Brief drops of a few seconds in the longest tunnels, but nothing disruptive. SoftBank is less consistent in tunnels on regional lines.
4G and 5G Speeds
Both carriers deliver comparable real-world 4G LTE speeds in major cities:
| Use case | Speed needed | Docomo (4G) | SoftBank (4G) |
|---|---|---|---|
| Browsing, Maps, social media | 1–5 Mbps | ✅ More than enough | ✅ More than enough |
| YouTube HD streaming | 5–10 Mbps | ✅ | ✅ |
| Video calls (Zoom, FaceTime) | 3–8 Mbps | ✅ | ✅ |
| Remote work with large files | 10+ Mbps | ✅ | ✅ (cities) |
5G is available on both networks in major cities (Tokyo, Osaka, Nagoya, Fukuoka). For most travelers, 4G LTE is more than sufficient — Docomo's 4G routinely reaches 50–150 Mbps in urban areas.
What About KDDI (au)?
Japan has a third major carrier: KDDI, sold under the au brand. Its coverage is comparable to SoftBank — excellent in cities, slightly behind Docomo in very rural areas. For travelers, the ranking is: Docomo first, KDDI second, SoftBank third for coverage depth.
Which Network Does PlanJapan Use?
PlanJapan eSIMs run on NTT Docomo — Japan's best-coverage network. No compromise: you get direct access to the #1 carrier's infrastructure from day one.
- Reliable connection in rural areas (Nikko, Hakone, Japanese Alps)
- Optimal coverage on Shinkansen lines
- Proven network on islands and remote regions
Frequently Asked Questions
Docomo or SoftBank: which is better for traveling Japan?
Docomo, hands down, for travelers going beyond major cities. It covers more rural areas, more Shinkansen tunnels, and more mountainous regions. SoftBank is fine if your itinerary is limited to Tokyo, Osaka, and Kyoto.
Does SoftBank work in rural Japan?
Yes, in most cases — but with more dead zones than Docomo. In mountain villages, Tohoku forests, or parts of inland Shikoku, SoftBank may lose signal where Docomo maintains a 4G connection.
Do both networks have 5G in Japan?
Yes. Docomo and SoftBank are both rolling out 5G in major cities. For a tourist trip, 4G LTE is more than enough — Docomo's 4G speeds average 50–150 Mbps in urban areas.
Does PlanJapan eSIM use Docomo or SoftBank?
Docomo exclusively. This is a deliberate choice: Docomo offers the broadest coverage in Japan, ensuring a reliable connection wherever your travels take you.
Can you switch between Docomo and SoftBank with an eSIM?
No — an eSIM is configured for a single network operator. PlanJapan eSIM is tied to Docomo and cannot roam onto SoftBank or KDDI. This isn't a limitation: since Docomo is Japan's most extensive network, there's no reason to switch.
Our Recommendation
For any trip to Japan, choose an eSIM on the Docomo network — and that's exactly what PlanJapan offers. No guesswork, no coverage compromise.
- Standard 1–2 week trip → 50 GB Japan eSIM
- Heavy use, remote work, or long stay → Unlimited Japan eSIM