Quick Answer: For overall coverage, docomo generally leads — particularly in rural and mountainous areas. au/KDDI is a close second with strong mountain coverage. SoftBank excels in dense urban areas. Rakuten Mobile is still expanding but covers most major cities. If you travel outside cities frequently, docomo-based plans (including ahamo) are typically the safest choice.
Coverage by Carrier: Where Each Network Shines
Japan is roughly 70% mountainous, which makes coverage outside cities a real differentiator. Each carrier publishes coverage maps on their website, but here's the practical reality:
| Area Type | docomo | au/KDDI | SoftBank | Rakuten |
|---|---|---|---|---|
| Urban (Tokyo, Osaka) | Excellent | Excellent | Excellent | Good–Excellent |
| Suburban | Excellent | Excellent | Good | Fair–Good |
| Rural / Countryside | Good–Excellent | Good | Fair | Poor–Fair (au roaming) |
| Mountain / Hiking | Good | Good | Fair | Poor |
| Underground / Metro | Excellent | Excellent | Excellent | Good |
Speed Test Averages
Based on aggregate speed test data from Japanese measurement services, typical download speeds in 2025-2026:
- docomo: 60-120 Mbps (4G), 200-500 Mbps (5G)
- au/KDDI: 55-110 Mbps (4G), 180-450 Mbps (5G)
- SoftBank: 50-100 Mbps (4G), 150-400 Mbps (5G)
- Rakuten: 30-80 Mbps (4G/5G on own network)
- MVNOs: 5-40 Mbps (varies heavily by time of day; expect 1-5 Mbps at lunch hour)
Sub-brands (ahamo, povo, LINEMO) generally deliver the same speeds as their parent MNO since they share the same network infrastructure.
5G Rollout Status
As of 2026, 5G in Japan is primarily available in major urban centers. The three established MNOs are expanding rapidly, but true nationwide 5G is likely still a few years away. For practical purposes, 4G LTE remains the backbone for most daily usage, and all carriers provide comprehensive 4G coverage in populated areas.
Frequency Bands: Why Your Foreign Phone Might Not Work
This is critical for foreign residents bringing phones from overseas. Japanese carriers use specific LTE frequency bands:
- docomo: Band 1 (2100MHz), Band 3 (1800MHz), Band 19 (800MHz — key for rural/indoor)
- au/KDDI: Band 1, Band 3, Band 18/26 (800MHz — essential for coverage)
- SoftBank: Band 1, Band 3, Band 8 (900MHz — "Platinum Band")
- Rakuten: Band 3 (1800MHz), Band 28 (700MHz — newly acquired)
If your phone lacks the low-frequency "Platinum Band" for your chosen carrier (Band 19 for docomo, Band 18 for au, Band 8 for SoftBank), you may experience poor indoor reception and weak signals in rural areas. Most iPhones sold globally since iPhone 7 support all Japanese bands. Some Android phones — particularly models from Chinese manufacturers sold in Southeast Asian markets — may lack certain bands.
VoLTE Compatibility
Japan has largely retired 3G networks. Voice calls now use VoLTE (Voice over LTE). Some foreign phones are not VoLTE-certified for Japanese carriers, which can mean: the phone connects to data but cannot make or receive voice calls. Before signing up, check your phone's VoLTE compatibility on the carrier's website. iPhones are generally fine; Android compatibility varies by model.
Q: How do I check if my phone supports Japanese frequency bands?
Check your phone's specs page for "supported LTE bands." You can also search your model on sites like kimovil.com or gsmarena.com. Match the listed bands against the carrier you want to use. At minimum, you want Band 1, Band 3, and the carrier's Platinum Band.
Q: Will my phone work on the Tokyo metro with Rakuten Mobile?
Generally yes. Rakuten has been installing base stations in Tokyo metro stations. However, coverage on some lines may still be patchy. The three established carriers (docomo, au, SoftBank) have more complete underground coverage.
Q: Is 5G worth paying extra for?
For most users, not yet. 5G coverage is limited to specific spots in major cities. The sub-brand plans (ahamo, povo, LINEMO) include 5G at no extra cost when available, so there is typically no need to pay a premium specifically for 5G.
Disclaimer: Speed test figures are approximate averages from third-party measurement services and will vary by location, time, and device. Coverage assessments are based on published carrier maps and user reports. Please verify current coverage on each carrier's official website.
