How to Get and Activate au by KDDI SIM Cards and eSIM: Guide for Tourists

KDDI is one of the major mobile operators in Japan, providing high-speed 4G LTE coverage across most of the country. As a tourist visiting Japan, getting an au by KDDI SIM card or Japan eSIM can help you stay connected with easy data, calls, and texting while exploring Japan.

In this guide, we’ll cover everything you need to know about using au by KDDI SIM card and eSIM in Japan, including coverage and speeds, best connectivity options, where to buy, activation, top-up, and more.


I. Quick facts about au by KDDI

 KDDI is the official name of the corporation, while au is the brand name for its mobile phone and internet services. Some quick things to know about KDDI’s mobile brand au:

  • au is a Japanese mobile phone operator, or au by KDDI, a brand marketed by KDDI in the main islands of Japan and by Okinawa Cellular in Okinawa for their mobile cellular services. It is the second-largest wireless carrier in Japan, with over 60 million subscribers.
  • au was founded in 1987 as DDI Cellular and was the first to launch a digital cellular network in Japan. The company adopted the name au in 2000.
  • au offers a wide range of mobile phone plans, including data, voice, and messaging plans. The company also offers a variety of other services, such as home broadband, television, and financial services.
  • au is known for its innovative marketing campaigns, which often feature popular Japanese celebrities. The company has also been a pioneer in the development of new mobile technologies, such as 4G and 5G.
  • au is a subsidiary of KDDI, a Japanese telecommunications conglomerate. KDDI is also the parent company of Okinawa Cellular.

So in summary, KDDI au gives you fast, reliable connectivity across almost all of Japan – perfect for tourists exploring the country.

au by kddi
au by KDDI

II. Japan KDDI Coverage and Speed in Japan

Next, let’s take a closer look at KDDI’s network coverage and typical speeds when using their service while in Japan as a visitor.

1. Au by KDDI coverage in Japan

au by KDDI coverage
au by KDDI coverage

Based on Opensignal’s October 2023 Mobile Network Experience Report for Japan, au’s coverage performance presents a mixed picture. While not the outright winner in any major category, it exhibits strengths and weaknesses worth mentioning:

  • Third Place in Coverage Experience: With a score of 7.8 on a 10-point scale, AU lags behind NTT Docomo (9.1) and Rakuten Mobile (7.9) in the overall coverage department.
  • Second Place in Availability: AU users spend 99.6% of their time connected to their network, only placing it behind NTT Docomo (99.7%).
  • Joint Winner in 5G Availability: AU users spend 9.9% of their time connected to 5G, ranking first among four operators.

Overall, AU provides a good 5G coverage experience in Japan, with a strong signal availability in most areas.

2. KDDI speed in Japan

Japan Mobile Operators Speed
Japan Mobile Operators Speed. Source: Opensignal

Based on Opensignal’s October 2023 Report for Japan, au’s speed shows both strengths and areas for improvement:

  • Overall Download Speed: Tied with NTT Docomo for 2nd place with a score of 44.7 Mbps, which is respectable but not the leader.
  • Overall Upload Speed: 3rd place with a score of 7.7 Mbps, falling behind both SoftBank and Rakuten Mobile.
  • 5G Download Speed: Joint champion with Rakuten Mobile, boasting a blazing-fast 177.4 Mbps, demonstrating strong performance in the new generation network.
  • 5G Upload Speed: 3rd place with a score of 14.9 Mbps, falling behind the leader Rakuten Mobile and SoftBank but still offering a significant improvement over 4G upload speeds.
  • Video Experience: AU ranked 2nd with a score of 69.7 points, indicating a generally good experience for streaming video but lagging behind SoftBank.
  • Consistent Quality: au scores 81.2%, tying with NTT Docomo for 3rd place. This means that users experience consistent performance for typical mobile tasks on AU’s network most of the time.

au’s speed performance is mixed. While it shines in 5G download speed and offers a decent 4G download speed, upload speed could be improved across both network generations.

III. What are the Best Connectivity Options of au by KDDI for Travelers to Japan?

au offers several connectivity options for travelers to Japan, catering to different needs and budgets. Here are some of the best options:

Option Description Pros Cons
Prepaid SIM with KDDI network Physical SIM card inserted into your phone, activated with a data plan Affordable. Wide coverage Requires SIM slot availability. Limited call/text options. Requires activation in Japan
eSIM with KDDI network Virtual SIM downloaded onto your phone, activated with a data plan Convenient, easy to switch between eSIMs. Fast and simple activation. Multiple device compatibility Not all phones support eSIM, check compatibility before purchase. May need Wi-Fi to activate upon arrival
KDDI Rental Wi-Fi Router Portable Wi-Fi hotspot device providing internet for multiple devices Connect multiple devices. No SIM slot needed. Battery powered: Portable and convenient, not dependent on phone battery Higher rental costs. Limited battery life, Requires charging, may not be ideal for long days out. Bulky to carry


  • For solo travelers with moderate data usage: eSIM is a convenient and cost-effective option.
  • For groups or heavy data users: rental Wi-Fi might be a better choice.
  • For short stays in urban areas: prepaid SIM/eSIMs offer flexibility and value.

IV. Best KDDI SIM cards for Tourists & Cost

Unfortunately, AU doesn’t have a tourist au by KDDI SIM card, only has subscription data plans, for Japanese residents. Foreigners can subscribe to an AU subscription only if they possess a visa other than a tourist visa.

Luckily, MVNOs (Mobile Virtual Network Operators) offer prepaid plans without contracts, using major networks, including KDDI. MVNOs are perfect for short trips as you don’t commit long-term.

Provider Data plans Data Price (USD)
Mineo (run on NTT Docomo network) Data Only 5GB ~US$8
Data Only 10GB ~US$11
Data Only 20GB ~US$13
Nuro (run by Sony) VS Plan 3GB ~US$4
VM Plan 5GB ~US$5
VL Plan 10GB ~US$8

MVNOs rent space on major networks at lower costs, passing savings to customers. They let you easily keep in touch during your stay without postpaid account requirements.

V. Does KDDI Japan support eSIM?

Yes, au also offers eSIM to compatible devices and the eSIM is also for subscription which means for Japanese residents only.

VI. Where can you buy a KDDI SIM card and eSIM?

Here are some quick recommendations on popular pick-up locations to buy au by KDDI SIM cards and eSIM in Japan:

1. Where to buy KDDI SIM for Japan

You have several 2 methods for buying an au by KDDI SIM card for Japan: in-person or online, depending on your needs and preferences:

  • KDDI stores (au shops): These are the official stores for KDDI mobile service. You can find au store in major cities and towns across Japan. They offer a wide range of SIM card plans and can help you choose the right one for your needs.
  • Electronics retailers: Many electronics retailers in Japan, such as Bic Camera, Yodobashi Camera, and Yamada Denki, also sell au by KDDI SIM cards or SIMs using the KDDI network.
  • Convenience stores: Some convenience stores in Japan, such as Lawson and FamilyMart, also sell KDDI SIM cards. This is a good option if you need a SIM card quickly and easily.
  • Online: You can also purchase KDDI SIM cards online from the KDDI website or third-party retailers. This is a good option if you’re not in Japan or if you want to compare prices from different vendors.
au store
au store

2. Where to buy Japan KDDI eSIM

Finding KDDI Japan eSIM is more limited for foreigners but you can try Japan eSIM from GIGAGO, with KDDI as the supporting network. 

Check out Gigago’s Japan eSIM powered by KDDI – starting from just $7.5 for 14 days of fast LTE data. No roaming fees – simply scan the QR code we email upon purchase. Travel to Japan has never been smoother. Purchase now to explore like a local upon arrival!

Japan eSIM
Japan eSIM

VII. How to Use and Activate au by KDDI Japan SIM/eSIM in Japan?

We’ve covered getting your hands on an au by KDDI SIM card or eSIM, next let’s discuss how you use and activate your KDDI mobile service while visiting Japan:

1. How to Use and Activate au by KDDI SIM Card in Japan?

If you purchase a standard au by KDDI SIM card package from a reseller, you’ll need to activate once inserting the nano-SIM into your phone. Just follow these simple steps:

  1. Unlock the phone and insert the KDDI SIM
  2. Power on the phone and disable data roaming
  3. Open the browser and it will redirect to the KDDI prepaid setup & activation portal
  4. Follow the prompts to select your prepaid plan and payment method
  5. Once activated, you’ll receive a confirmation SMS from KDDI

Then you’re all set! The SIM card will connect you to KDDI’s fast LTE network across Japan so you can start using mobile data, plus placing calls & texts if you choose a voice package.

2. How to Use and Activate KDDI eSIM?

Getting started with an AU eSIM for Japan is quite easy as follows:

  1. Install the eSIM
  2. Activate the eSIM
  3. Set up the eSIM
  4. Start using the eSIM: Once the eSIM is activated and set up, you can start using its services.

eSIM activation is quick and convenient to get connected on KDDI’s network before landing in Japan.

VIII. How to top-up KDDI Japan SIM/eSIM

If you start to run short on data or calling balance with your au by KDDI SIM card/eSIM, you have a couple of quick ways to top-up prepaid credit:

  • Online – Revisit the KDDI prepaid portal and log in to add more yen by credit card to your SIM profile
  • Stores – Take SIM card to BIC, Yodobashi, or other electronic stores with SIM section to top-up
  • Vending – Purchase prepaid voucher cards from AU vending machines and add them to your SIM

So it’s straightforward to add more data & call credit even mid-trip – just monitor your usage in Japan and top-up online when running low.

So au by KDDI SIM cards make it simple to renew your balance from their online account dashboard while traveling in Japan. This allows you to keep enjoying KDDI’s stellar nationwide 4G speeds and coverage while exploring the Land of the Rising Sun!

X. FAQs about au by KDDI in Japan

Is KDDI or Docomo better in Japan?

For pure network quality and speeds, NTT Docomo edges out KDDI. However Docomo charges higher prices, so KDDI delivers excellent 4G coverage for more affordable rates.

Does the au by KDDI SIM card work in the USA?

No – KDDI SIM cards including eSIM will only provide service inside Japan. International roaming is not supported on prepaid tourist plans. Either turn off mobile data or use WiFi when outside the country.

Can I make calls & text with au by KDDI SIM card?

Entry-level KDDI data SIM cards only provide mobile internet access. To add calling & SMS, choose a KDDI voice & data plan that includes a local phone number. Useful for longer stays.

XI. Conclusion

So in summary, getting a Japan eSIM setup with KDDI network is a great way for tourists on short or extended visits to stay conveniently connected with mobile data and calls across Japan. With affordable prepaid packages, lightning-quick 4G speeds, and near nationwide population coverage, KDDI connectivity keeps your Japan travel adventures flowing smoothly whether hiking Mount Fuji or lost in Tokyo’s neon-lit side streets!