Japan Mobile Network Coverage Guide: Which eSIM Works Where?

Japan's Mobile Networks

Japan has three major mobile carriers that eSIM providers connect to:

NTT Docomo

• Coverage: Best nationwide coverage, including rural and mountainous areas
• Strength: Reliable on Shinkansen and in smaller towns
• 5G: Expanding in major cities
• eSIM providers using Docomo: Ubigi, many smaller providers

KDDI au

• Coverage: Excellent in cities and along major transport routes
• Strength: Strong performance on bullet trains and in suburban areas
• 5G: Good 5G coverage in Tokyo, Osaka, Nagoya
• eSIM providers using au: Saily, Airalo (partial), ESIMJAPAN

SoftBank

• Coverage: Good in urban areas, weaker in rural regions
• Strength: Competitive 5G speeds in cities
• eSIM providers using SoftBank: Airalo (partial), some budget providers

Coverage by Region

Tokyo & Osaka

All three carriers provide excellent 4G and growing 5G coverage. You won't have connectivity issues in major cities regardless of which provider you choose.

Kyoto & Nara

Good coverage from all carriers. Docomo tends to perform slightly better in temple areas and surrounding hills.

Hokkaido

Docomo has the best coverage in Hokkaido's rural areas. If you're visiting beyond Sapporo, prioritize Docomo-based providers.

Okinawa

All carriers cover the main island well. Outer islands may have patchy coverage — Docomo is generally most reliable.

Rural & Mountain Areas

For hiking, rural onsen towns, or off-the-beaten-path destinations, NTT Docomo is the safest choice. au is second best. SoftBank may drop in remote areas.

Shinkansen (Bullet Train) Coverage

Modern Shinkansen routes have good coverage from all carriers, with brief drops in tunnels. The Tokaido Shinkansen (Tokyo-Osaka) has the best coverage. Newer routes in northern Japan may have more tunnel interruptions.

What to Look For When Choosing

1. Check which network your eSIM provider uses — This information is in the plan details

2. If traveling beyond major cities, prioritize Docomo or au

3. 5G is nice but not necessary — Japan's 4G LTE is fast enough for all traveler needs

4. Dual-carrier plans (providers that use both Docomo and au) offer the best overall coverage

Speed Test Data

We tested 6 providers across Tokyo, Osaka, Shinkansen, and rural areas. See the full results: Japan eSIM Speed Test 2026

Quick summary:

• Fastest in cities: Saily (KDDI au) — 295 Mbps peak in Shibuya
• Best rural coverage: Ubigi (NTT Docomo) — stable 4G even in Hokkaido countryside
• Best all-rounder: Airalo — consistent 71 Mbps average across all locations

Provider Reviews by Network

• NTT Docomo: Ubigi → | Full Review — Best for rural Japan
• KDDI au: Saily → | Full Review — Fastest city speeds
• KDDI au + SoftBank: Airalo → | Full Review — Widest plan selection

Find Your Plan

Filter by network type on our comparison page — select "4G" or "5G" to narrow results.