FAQ
Service Overview
What is Sakura SIM?
Sakura SIM is a local eSIM service that allows you to directly use the network of Japan's major telecommunications carrier, au (KDDI). Unlike roaming eSIMs that go through overseas telecommunications companies, Sakura SIM connects directly to KDDI's core network, resulting in fast communication speeds, minimal latency, and extremely stable data. You can easily use reliable Japanese-quality communications while traveling in Japan or returning home temporarily.
Where can I use it?
Sakura SIM is a service exclusively for use within Japan. It is optimized for overseas travelers visiting Japan and Japanese people temporarily returning to Japan.
How is it different from other eSIMs (Airalo, Nomad, etc.)?
Many SIMs, such as Airalo and Nomad, are "roaming eSIMs" that communicate via overseas servers. This can result in slower connections and less stable speeds. Sakura SIM, on the other hand, is a "local eSIM" that connects directly to the au (KDDI) network, resulting in extremely fast response times, achieving up to five times faster speeds and roughly one-tenth the communication latency. As a result, video streaming and map apps run smoothly, allowing you to enjoy a comfortable internet environment even while traveling.
What is the difference between signing up for an au line at an au Shop or the au online store in Japan and Sakura SIM?
To sign up with KDDI in Japan, you will need to provide a Japanese address and identification , and the process takes time.
On the other hand, Sakura SIM is an eSIM service that can be easily purchased online .
Once you add it to your cart and make the payment, you will receive a QR code via email. Simply add it to your smartphone to start using it .
No Japanese address or identification documents are required, making it convenient and ideal for temporary return to Japan, travel, or short- to medium-term stays .
Is it more convenient than pocket Wi-Fi?
Sakura SIM can be installed directly on your smartphone, eliminating the need to carry around or charge a device like with pocket Wi-Fi. Furthermore, with an unlimited data plan, you can use social media and watch videos without worrying about data usage. It also supports tethering, so you can share your data with other devices.
Is Sakura SIM recommended for traveling to Japan?
Sakura SIM is the perfect eSIM for travelers to Japan. It offers unlimited access to au (KDDI)'s high-quality lines at an affordable price, and is very easy to set up. Whether you're traveling for business or pleasure, you'll enjoy a comfortable communication environment.
Compatible devices and settings
How can I check which devices support eSIM?
If you dial *#06# on your smartphone and the number "EID" appears, your device is eSIM-compatible. Most recent models, including the iPhone XS and later, Samsung Galaxy, and Google Pixel, are compatible. If the number does not appear, please check the following:
If EID is displayed in Settings > About Device > Other Information, the device is eSIM compatible.
*Menu names vary depending on the model, so please check for yourself.
How do I set up an eSIM?
After purchase, a QR code and setup instructions will be sent to your registered email address.
- Go to "Settings" → "Mobile" → "Add eSIM"
- Scan the QR code you received
- Set Sakura SIM to "Mobile Data"
Communication will begin automatically when you arrive in Japan. (*With iOS 17.4 or later, you can also set it up by simply pressing and holding the QR code.)
When should I set it up?
We recommend setting up your plan in advance in a location with a stable internet connection. Your data plan will be activated automatically once you arrive in Japan.
After setting up the eSIM, do I need to do anything to activate it?
No special operations are required. Once the setup is complete, communication will begin immediately after you arrive in Japan.
Can I transfer my eSIM to another device?
Once installed, an eSIM cannot be transferred to another device. If you want to use it on a new device, you will need to purchase a new eSIM.
I deleted my eSIM. Can I have it reissued?
It cannot be reissued. Please be careful not to delete it by mistake. Please note that it will be automatically suspended after the expiration date, so there is no problem if you do not delete it.
Can I use it with a physical SIM?
Yes. If you have a dual SIM compatible device, you can use your regular SIM for calls and SMS, and the Sakura SIM for data communication. However, please note that international roaming charges may apply when making calls or sending SMS.
Usage and Communication
When should I start using it?
Usage begins when you connect to an au (KDDI) network in Japan. The plan's days are counted from 23:59 Japan time on the day of connection, with the first day counted. (Example: If you connect to a 7-day plan on June 10th, your usage period ends on June 16th at 23:59.)
How can I check if I can't communicate?
Please check the following in order:
- Is "Mobile Data" turned on?
- Is "Mobile Data Communication" set to Sakura SIM?
On iPhone, you may occasionally see the message "Activation failed," but if Sakura SIM is displayed in the settings, you can use it normally.
Can I use tethering?
Yes, if your device supports tethering, you can use it. It is also easy to share with other devices.
Can I make calls and send SMS?
Sakura SIM is for data communication only. Voice calls and SMS cannot be used. However, you can make calls using internet calling apps such as LINE, WhatsApp, and Messenger.
Can I still use my original phone number?
Yes. Sakura SIM is for data only, so you can continue to use your current number for calls and SMS. If you have a dual SIM-compatible device, you can use your regular number for calls and Sakura SIM for data at the same time.
What frequency bands does Sakura SIM support?
Sakura SIM uses the au (KDDI) network and is compatible with 5G and 4G (LTE) communications. It can be used in the following frequency bands.
- 5G 700MHz n28
- 5G 1.7GHz n3
- 5G 2.5GHz n41
- 5G 3.5GHz n77/n78
- 5G 3.7GHz n77/n78
- 5G 4.0GHz n77
- 5G 28GHz n257
- 4G (LTE) 700MHz Band 28
- 4G (LTE) 800MHz Band 18 / Band 26
- 4G (LTE) 1.5GHz Band 11
Purchases, Plans, and Refunds
When will my eSIM arrive?
After completing the purchase process, you will receive a QR code and setup instructions via email. There is no need to install any apps.
How long does the plan last and how does it count?
The first day is the day you connect to the au (KDDI) network locally, and the plan is valid for the number of days purchased, until 23:59 Japan time. (Example: A 3-day plan starts at 19:00 on June 19th → ends at 23:59 on June 21st)
Can I change or cancel my plan after purchasing?
Due to the nature of digital products (eSIM), cancellations, refunds, and plan changes are not possible after purchase. Please check the plan details and whether your device is eSIM compatible before purchasing.
What if I want to extend the period?
Existing plans cannot be extended or topped up. If you wish to continue using the service, please purchase a new eSIM.
Can I get a refund if I no longer plan to use the service?
Unfortunately, we do not offer cancellations or refunds after a purchase has been completed.
What if my device doesn't support eSIM?
Because eSIMs are electronically issued products, refunds are not possible even if the device is not compatible. Please make sure your device is eSIM compatible before purchasing.
Can I delete Sakura SIM's eSIM once I've finished using my data plan?
Yes, you can delete it. However, the eSIM will automatically stop functioning once the usage period has expired, so there is no need to delete it.
Can I check the amount of data I have used?
This service is provided on an unlimited plan and data usage cannot be confirmed individually.
When can I set it up?
Setting up an eSIM requires a stable internet connection.
Activate your SIM
It says "Failed to activate on iPhone".
If this message appears, it is most likely activated. Go to "Settings" → "Mobile Data" and check that the eSIM you named is listed in the SIM column. If it is displayed, it has been activated correctly. This message often appears when installing overseas, but once you arrive in Japan, you will be able to use it without any problems, so please do not delete it.
The activation never finishes.
Activation may take some time depending on your device and internet connection. Depending on your location, it may take up to an hour, so please be patient.
What is the activation deadline?
The activation deadline is the date by which you can start using your eSIM. With Sakura SIM, the activation deadline is set to 180 days from the date of SIM issuance. After this deadline, the SIM will automatically be disconnected from the au (KDDI) network and you will no longer be able to communicate.
What is the relationship between the activation deadline and the plan expiration date?
Sakura SIM will automatically become unusable on the earlier of the following dates:
- Activation period (= 180 days from SIM issuance)
- Package expiration date (the date when the purchased plan ends)
Whichever expiration date comes first, the SIM will become invalid at that point.
What happens if I start using it close to the expiration date?
For example, if you are using a "31-day plan" with an activation deadline of December 31, 2025, even if you activate (start using) the SIM on December 29, 2025, you can only use the SIM until December 31, 2025. In this way, even if you have days remaining on your plan, communications will automatically end once the activation deadline has passed.
Why can I still use it temporarily after the activation deadline has passed?
After the activation deadline, the system will process network disconnections in sequence, so you may be able to connect to the network temporarily even after the deadline.