au by KDDI Speed Test - Japan | Kencang
Test your au by KDDI internet speed in Japan
www.au.comau by KDDI is Japan's second-largest telecommunications carrier with over 71 million subscribers. KDDI operates its own fiber network (au Hikari) and a nationwide 5G and 4G LTE mobile network. The company also runs UQ Mobile as a budget sub-brand on the same au network.
About au by KDDI
KDDI was formed in 2000 through the merger of DDI (Daini Denden), KDD (Kokusai Denshin Denwa), and IDO. The au mobile brand launched in 2001 and grew to become Japan's second-largest carrier behind NTT DoCoMo. KDDI is headquartered in Shinjuku, Tokyo.
Unlike DoCoMo and SoftBank, KDDI operates its own independent fiber network called au Hikari, separate from NTT's FLET'S Hikari infrastructure. This gives au Hikari users a different network path that can be less congested during peak hours. au Hikari is available in most of Japan except the Kansai and Chubu regions, where regional providers eo Hikari and Commufa operate.
KDDI also owns UQ Mobile, a budget brand that uses the full au 4G and 5G network at lower prices. In August 2025, KDDI revised pricing across most au plans, with increases of JPY 110-550 per month on select tiers.
au by KDDI Plans and Services
au by KDDI offers several internet plans across different technologies and price points.
au's flagship mobile plan is Unlimited MAX+ at JPY 7,238 per month for unlimited 5G data. This plan includes au Starlink Direct for satellite-to-phone connectivity and au 5G Fast Lane for priority network access in congested areas. Family discounts and au Smart Value fiber bundles can reduce the price by JPY 1,760 or more.
For budget users, UQ Mobile offers plans from JPY 2,365 per month for 4 GB with data rollover. UQ Mobile runs on the same au network with identical coverage. KDDI also offers specialized plans for users aged 12 and under, 16 and under, and seniors aged 60 and over.
au Hikari fiber broadband provides 1 Gbps service at JPY 5,610 per month and 10 Gbps at JPY 7,018 per month for detached houses. The au Smart Value discount saves JPY 550-1,100 per mobile line when bundled with au Hikari.
au by KDDI Internet Plans
| Plan | Speed | Price | Features |
|---|---|---|---|
| au Unlimited MAX+ mobile | 5G/4G LTE | JPY 7,238/month |
|
| UQ Mobile Mini Plan mobile | 4G LTE/5G | JPY 2,365/month |
|
| au Hikari Home 1 Giga fiber | 1 Gbps | JPY 5,610/month |
|
| au Hikari Home 10 Giga fiber | 10 Gbps | JPY 7,018/month |
|
Prices and availability may vary by location. Contact au by KDDI for current offers.
au by KDDI Coverage by Region
au by KDDI performance varies by location. Coverage density, local infrastructure, and network congestion affect speeds in each market.
Tokyo Metropolitan Area (Kanto)
Highest concentration of au 5G base stations and au Hikari coverage
Osaka-Kobe-Kyoto (Kansai)
au mobile works fine but au Hikari fiber cannot be ordered in Kansai
Nagoya and Chubu Region
au mobile service available but fiber bundles require Commufa partnership
Hokkaido, Tohoku, Kyushu
au Hikari is available in these regions, making it an advantage over areas where it is not
Is au by KDDI Right for You?
Every provider has trade-offs. Here is how au by KDDI performs based on real-world usage and customer feedback.
Strengths
- Independent fiber network (au Hikari) separate from NTT FLET'S. Less congestion
- au Starlink Direct satellite connectivity available on premium plans
- UQ Mobile sub-brand offers au network quality at budget prices
- 10 Gbps fiber available in many areas. Faster than most NTT-based options
- Strong 5G coverage in urban areas across all major cities
- au Smart Value bundle discounts save up to JPY 1,100 per mobile line
- Specialized plans for children, teens, and seniors
Weaknesses
- au Hikari not available in Kansai and Chubu regions
- Premium plans at JPY 7,238 are among the most expensive in Japan
- August 2025 price increases raised monthly costs by JPY 110-550
- Fewer subscribers than DoCoMo. Smaller overall network investment
- 5G mmWave coverage is limited to select spots in major cities
Best For
- Users who want an independent fiber network separate from NTT
- Families that bundle au Hikari with multiple au mobile lines
- Budget users on UQ Mobile who want au network quality
- Users interested in satellite connectivity via au Starlink Direct
- Gamers and heavy users who want 10 Gbps fiber
Not Ideal For
- Users in Kansai or Chubu regions where au Hikari is unavailable
- Budget-focused users. Rakuten Mobile offers unlimited data cheaper
- Users who want the largest possible 5G footprint (DoCoMo is wider)
- Those who prefer fully online-only account management
How au by KDDI Compares
Side-by-side comparison of au by KDDI against major competitors in Japan.
| Competitor | Speed | Price | Coverage | Verdict |
|---|---|---|---|---|
| Ntt Docomo | Similar 5G speeds of 500-2,000 Mbps in covered areas. DoCoMo has wider 5G coverage. au leads with Starlink satellite. | au Unlimited MAX+ at JPY 7,238. DoCoMo MAX at JPY 7,315. Similar pricing for premium tiers. DoCoMo ahamo is cheaper than UQ Mobile. | Both cover all of Japan with 4G. DoCoMo has more 5G base stations. au has unique satellite coverage via Starlink Direct. | Choose au for independent fiber (au Hikari) and Starlink satellite access. Choose DoCoMo for widest 5G coverage and ahamo value. |
| Softbank | Comparable 5G speeds in major cities. SoftBank leads in 5G time availability. au offers 10 Gbps fiber. | au UQ Mobile from JPY 2,365. SoftBank LINEMO from JPY 990. LINEMO is cheaper for basic plans. | Both have strong nationwide 4G and growing 5G. au has satellite backup via Starlink. | Choose au for au Hikari fiber bundles and satellite connectivity. Choose SoftBank for cheaper LINEMO plans and PayPay integration. |
Troubleshooting au by KDDI Issues
Common au by KDDI connection problems and how to fix them.
au mobile speeds are slower than expected on 5G or 4G
Cause: Network congestion in busy areas, distance from tower, or device not set to 5G mode.
- Check if your phone is connected to 5G or 4G in the status bar
- Move to an outdoor location with clear line of sight to towers
- Toggle airplane mode on and off to force a new network connection
- Restart your phone to clear any cached network settings
- Check au service status at au.com for maintenance or outages in your area
au Hikari fiber is slower than the advertised 1 Gbps or 10 Gbps
Cause: Router limitations, Wi-Fi interference, or device not supporting gigabit speeds.
- Test with a wired Ethernet connection directly to the router
- Check that your router supports Wi-Fi 6 or later
- Place the router in a central location away from walls and appliances
- For 10 Gbps service, verify your device has a 10 Gigabit Ethernet port or Wi-Fi 7
au by KDDI History
Key milestones in au by KDDI development and network expansion.
KDDI formed through merger of DDI, KDD, and IDO
Launched au mobile brand across Japan
au reached 14 million mobile subscribers
Acquired Hanaro Telecom (now SK Broadband) in South Korea
Launched au Hikari fiber broadband service for residential users
Launched commercial 5G service in March
Introduced au Starlink Direct satellite-to-phone service on premium plans
Revised pricing across major plans in August with increases of JPY 110-550
Test Your au by KDDI Speed
Run a free speed test to check if au by KDDI delivers the speeds you are paying for. Test during peak evening hours for the most realistic results. Compare your results against au by KDDI advertised speeds above.
au by KDDI Speed Test FAQ
What network does au use in Japan?
au operates KDDI's own mobile network in Japan, independent from NTT DoCoMo and SoftBank. KDDI runs its own 5G, 4G LTE, and 3G cell towers covering all 47 prefectures. For fiber broadband, au Hikari uses KDDI's own fiber network that is separate from NTT's FLET'S Hikari infrastructure. UQ Mobile, KDDI's budget brand, runs on the same au network. This independent infrastructure means au Hikari can be less congested than NTT-based fiber in some areas.
Is au Hikari available in Osaka and Kyoto?
No, au Hikari fiber broadband is not available in the Kansai region (Osaka, Kyoto, Hyogo, Nara, Shiga, Wakayama) or the Chubu region (Aichi, Gifu, Mie, Shizuoka). In Kansai, the regional fiber provider is eo Hikari (Optage), which offers comparable speeds and KDDI partnership discounts. In Chubu, Commufa provides regional fiber. au mobile service works normally in all regions regardless of au Hikari availability.
How does UQ Mobile compare to au plans?
UQ Mobile uses the exact same au 4G and 5G network with identical coverage and speeds. The difference is pricing and features. UQ Mobile starts at JPY 2,365 per month for 4 GB with data rollover, while au's Unlimited MAX+ costs JPY 7,238 for unlimited data. UQ Mobile does not include au Starlink Direct satellite connectivity or au 5G Fast Lane priority access. UQ Mobile plans are available at UQ stores and online. au plans can be purchased at au stores, which offer more in-person support options.