Japan eSIM: Speed, Throughput and Real Connection Test (2026)

TL;DR

In Japan, an eSIM on the NTT Docomo network delivers speeds of 30 to 80 Mbps on 4G LTE and 100 to 300+ Mbps on 5G — more than enough for Maps, HD streaming, video calls and social media. Performance varies by area (city center vs countryside), time of day and the carrier used. At PlanJapan, our eSIMs connect directly to the Docomo network with no intermediary, guaranteeing the best available speeds.

Average speeds in Japan: what to realistically expect

Japan is regularly ranked among the top 10 fastest countries for mobile internet (source: Ookla Speedtest Global Index). Unlike some destinations where the network is unpredictable, speeds here are stable and high in the vast majority of situations.

Here are the average speeds you can expect by network technology:

Technology	Average download	Average upload	Latency
4G LTE	30 – 80 Mbps	10 – 30 Mbps	15 – 35 ms
4G LTE-Advanced	80 – 150 Mbps	20 – 50 Mbps	10 – 25 ms
5G (sub-6 GHz)	100 – 300 Mbps	30 – 80 Mbps	5 – 15 ms
5G (mmWave, limited areas)	300 – 1,000+ Mbps	50 – 200 Mbps	< 10 ms

In practice, on the NTT Docomo network used by PlanJapan, the vast majority of travelers see between 40 and 100 Mbps download in urban areas — a speed that lets you do everything without ever feeling any lag.

Japanese carrier comparison: Docomo vs SoftBank vs KDDI

Not all eSIMs connect to the same network. The choice of underlying carrier directly influences the speeds you'll get. Japan has three major carriers, and their performance differs significantly:

Carrier	Average download (4G)	National coverage	Strengths
NTT Docomo	50 – 80 Mbps	99.9%	Best rural coverage, legacy leader
KDDI (au)	40 – 70 Mbps	99.5%	Good in urban areas, solid in mountains
SoftBank	35 – 65 Mbps	98%	Fast in cities, more limited rural coverage

NTT Docomo is Japan's legacy carrier and the one that invests the most in its network. That's why PlanJapan chose to connect exclusively to Docomo: you get the best coverage and the most stable speeds, wherever you go in Japan.

Note: some eSIM providers don't specify which carrier they use. If your eSIM connects to a SoftBank network or an MVNO (virtual carrier), speeds can be 20 to 40% lower compared to a direct Docomo connection.

Speed test by area: Tokyo, Osaka, Shinkansen and countryside

Speeds vary noticeably depending on where you are. Here's what to expect in the most common travel situations:

City center (Tokyo, Osaka, Kyoto)

This is where speeds are highest. In neighborhoods like Shinjuku, Shibuya, Umeda or Namba, you'll commonly see:

• 4G: 50 to 100 Mbps download
• 5G: 150 to 400 Mbps in covered zones (major stations, shopping streets)
• Latency: 10 to 25 ms

Even during peak hours, speeds rarely drop below 20 Mbps — a floor that remains comfortable for all common uses.

Subway and underground stations

Unlike many countries, the Japanese subway is covered in 4G across nearly all stations and on most lines. In Tokyo, subway lines (Tokyo Metro and Toei) have antennas in the tunnels. You can send messages, use Maps and browse social media even between stations.

Subway speeds range from 10 to 40 Mbps — sufficient for everything except continuous HD video streaming.

Shinkansen (bullet train)

The Shinkansen is a special case. Connection is maintained on most lines, but speeds fluctuate:

• In stations and urban areas: 30 to 80 Mbps
• In open countryside: 10 to 50 Mbps
• In tunnels: brief drop (a few seconds), automatic reconnection

The Tokyo-Kyoto route (Tokaido Shinkansen) is generally well covered. You can work, send messages and use Maps without issues. Video streaming works but may experience brief interruptions in long tunnels.

Rural areas and countryside

The Docomo network covers 99.9% of Japanese territory, but speeds logically drop in rural areas. Expect:

• Villages and small towns: 10 to 30 Mbps (4G)
• Mountainous areas (Japanese Alps, Hakone): 5 to 20 Mbps
• Remote islands (some Okinawa islands, Yakushima): 3 to 15 Mbps

Even at the 3 to 5 Mbps floor, you can use Google Maps, send photos on WhatsApp and make video calls. The connection virtually never "drops" — it slows down but remains functional.

What these speeds actually mean in practice

Mbps numbers don't speak to everyone. Here's what these speeds actually mean for your daily traveler usage:

Usage	Required speed	Works everywhere in Japan?
Google Maps / GPS navigation	< 1 Mbps	Yes, even in rural areas
WhatsApp / LINE (messages + photos)	1 – 2 Mbps	Yes, everywhere
Instagram / TikTok (scroll + stories)	2 – 5 Mbps	Yes, everywhere
FaceTime / Zoom (video call)	3 – 5 Mbps	Yes, except brief tunnels
HD video streaming (YouTube, Netflix)	5 – 10 Mbps	Yes in cities, variable on Shinkansen
4K streaming	25+ Mbps	In cities only
Large file downloads	50+ Mbps	In cities, fast

In summary: with a minimum speed of 5 Mbps (which you'll have virtually everywhere in Japan with Docomo), you cover 95% of a traveler's needs. Japan is not a country where you end up "without internet" — it's quite the opposite.

Why some eSIM providers are slower

You may have read reviews from travelers complaining about poor speeds with their eSIM in Japan. This isn't a Japanese network problem — it's a provider problem. Here's why.

Routing through foreign servers

Some eSIM providers (notably Holafly, Airalo and other international MVNOs) don't connect directly to the Japanese network. Your traffic is routed through intermediary servers located in Hong Kong, Singapore or Europe. The result:

• Latency multiplied by 3 to 5 (50 to 150 ms instead of 15 to 30 ms)
• Throttled speeds: the intermediary relay becomes a bottleneck
• Misleading speedtest: the test measures speed to the relay server, not to the final server

Fair-use and hidden throttling

Some "unlimited" plans actually apply a fair-use policy: after a certain data volume (often 500 MB to 1 GB per day), speeds are reduced to 128 or 256 Kbps — essentially unusable for anything beyond text. These conditions are rarely highlighted at the time of purchase.

The PlanJapan advantage: direct Docomo connection

At PlanJapan, your eSIM connects directly to the NTT Docomo network, with no intermediary server or foreign routing. Concretely, this means:

• The speeds you measure with Speedtest match the actual Docomo network speeds
• Latency stays low (15 to 30 ms on 4G)
• No throttling or hidden fair-use — you use your data allowance at the network's maximum speed

To learn more about 5G coverage in Japan, see our complete guide to 5G and eSIM coverage.

How to test your speed in Japan

If you want to check your connection speed yourself once on-site, here's how.

Best speed test apps

Application	Advantages	Disadvantages
Speedtest by Ookla	Servers in Japan, detailed results (ping, jitter, download, upload)	Uses ~50 MB per test
Fast.com (Netflix)	Simple, fast, no ads	Measures download only
nPerf	Complete test + streaming + browsing	Slightly cluttered interface

Tips for an accurate test

• Choose a Japanese server (Tokyo or Osaka) in Speedtest — a foreign server will skew results
• Close background apps: iCloud, automatic updates and cloud sync consume bandwidth
• Test at different times: speeds are higher in the morning (6-8 AM) and lower at peak hours (12-1 PM, 6-8 PM)
• Watch your data usage: each Speedtest run uses about 50 MB — don't run 20 tests per day if you have a limited plan

Factors that affect your eSIM speed

If your speed seems lower than expected, it's not necessarily an eSIM problem. Several external factors influence connection speed:

• Time of day: peak hours (8-9 AM, 12-1 PM, 6-8 PM) reduce speeds by 20 to 40% in busy areas
• Number of users: a spot like Shibuya Crossing at 6 PM concentrates thousands of smartphones on the same antennas
• Your position: inside a thick concrete building, signal can be weakened — move closer to a window
• Weather: heavy rain (rainy season in June-July) can slightly affect signal, especially in rural areas
• Your smartphone: an iPhone 14 or newer will pick up 5G signal better than an older model limited to 4G
• Airplane mode: if your connection seems slow, toggle airplane mode on then off — this forces a reconnection to the best-performing antenna

Frequently asked questions

What speed can I expect with an eSIM in Japan?

On 4G LTE, expect 30 to 80 Mbps download in urban areas, and 10 to 30 Mbps in rural areas. On 5G (available in major cities), speeds reach 100-300+ Mbps. These figures correspond to the NTT Docomo network used by PlanJapan.

Is the speed sufficient for video streaming and FaceTime calls?

Yes, easily. HD streaming requires about 5 Mbps and a FaceTime call about 3 Mbps. Even in Japan's least-covered areas, you generally exceed these thresholds. 4K streaming (25+ Mbps) is reserved for urban areas and WiFi or 5G connections.

Why is my eSIM slower than expected?

Three main causes: (1) your provider routes traffic through foreign servers instead of a direct connection to the Japanese network, (2) a hidden fair-use or throttling policy reduces your speed after a certain volume, (3) you're in a very busy area during peak hours. With PlanJapan, causes 1 and 2 are eliminated since the connection is direct on Docomo with no throttling.

How do I test my eSIM speed in Japan?

Download the Speedtest by Ookla app or go to Fast.com. Select a server located in Japan (Tokyo or Osaka) for accurate results. Note: each test uses approximately 50 MB of data.

Does PlanJapan throttle the connection after a certain volume?

No. At PlanJapan, there's no fair-use or throttling. You use your data allowance (10, 20 or 50 GB) at the NTT Docomo network's maximum speed. When the allowance is used up, the connection stops — it's not artificially slowed down.

Does the Shinkansen have good internet connectivity?

Yes, overall. Speeds range from 10 to 80 Mbps depending on the section. The Tokaido line (Tokyo-Kyoto-Osaka) is the best covered. You can use Maps, send messages and browse without issues. Video streaming works but may experience brief interruptions in tunnels.

Our recommendation

Japan offers one of the best mobile networks in the world — but you still need to choose an eSIM provider that gives you access to that network without intermediaries. Too many travelers discover on-site that their "budget" eSIM routes traffic through foreign servers, with speeds cut by half or more.

At PlanJapan, your eSIM connects directly to the NTT Docomo network — the fastest and best-covered in Japan. No relay servers, no fair-use, no hidden throttling.

• Standard trip (1-2 weeks, Maps + social media) — 20 or 50 GB eSIM
• Intensive use (streaming, hotspot, remote work) — 50 GB eSIM

To compare PlanJapan with other providers, see our comparison of the best eSIMs for Japan.