09 November 2026 • 3 min read
Top Flexiroam Alternatives for Easy Connectivity
Unlimited
Japan Unlimited SIM Card
Truly Unlimited (No FUP) • 4–31 days
4.8|Based on 567 Reviews4.8 out of 5 stars based on 567 reviews
KDDI (au)5G/4G
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Important Information
IMPORTANT: Competitors advertising "Unlimited Data for Japan" without addressing any limits or throttling may be misleading. If you find ambiguous language regarding potential data slowdowns attributed to factors beyond their control and assurance speeds will normalize the next day, it typically indicates the presence of an undisclosed daily usage caps. We strongly advise reaching out to them directly or thoroughly reviewing their website to clarify these restrictions. Our Unlimited Japan Data SIM card has No daily data caps and is purely unlimited. Hotspot/tethering limit varies by plan: 4 days (3GB); 7 days(6GB); 10 days(9GB); 15 days (15GB); 31 days (30GB)
Data
Unlimited Data
Validity
15-31 Days
Data Speed
4G/5G
Calls
Not included (Data-Only)
Phone Number
N/A
Texts
Not included (Data-Only)
Hotspot
Varies by plan
Product Add-on
N/A
Price Drop? Get a Refund
If the price drops within 30 days, we'll refund the difference!
Seen it for less? We'll beat it!
If you find the same SIM for less, we'll beat the price by 5%!
SimCorner Japan Unlimited SIM Card
Stay seamlessly connected across Japan with the SimCorner Japan Unlimited SIM Card. Tailored for high-volume data users, digital nomads, and content creators, this physical SIM delivers reliable 5G/4G coverage nationwide on top Japanese networks.
Plan Details
Truly Unlimited High-Speed Options: Choose between non-stop unlimited data with zero speed caps or a daily high-speed pool (e.g., 3GB/day full speed, then unlimited at 128Kbps).
4 to 31 days: Available in multi-day options, including 15-day and 31-day validity periods to align with your trip.
au (KDDI) Network: Connect to the au (KDDI) network for 5G/4G mobile connectivity across Japan.
Uncapped Hotspot: Share your mobile connection with secondary devices, tablets, or travel partners.
Universal 3-in-1 SIM: Trio-cut format (Nano, Micro, Standard) fits any unlocked smartphone, tablet, or portable Wi-Fi dongle.
Scheduled Activation: Simply register your travel date, and your Japan Unlimited SIM Card activates automatically upon your arrival.
Convenience Features
Complete Coverage: Enjoy 5G/4G access across all of Japan—from major hubs like Tokyo, Osaka, and Kyoto to scenic destinations like Mt. Fuji, Hakone, and Okinawa. Experience steady signal strength on trains, in subway stations, and everywhere in between.
Keep Home Number: Your WhatsApp and iMessage stay linked to your primary number, so friends and family can reach you as usual.
Plug & Play Convenience: No complex settings, no identity verification checks, and no unexpected roaming fees. Just insert and connect.
No Expiration Before Use: Buy early with confidence. Your card remains valid until you choose to activate it—no pre-activation expiry window.
Compare & Choose the Best eSIM Plan!
Japan SIM Card FAQs: All You Need to Know
Who is SimCorner?
SimCorner is your trusted global provider of travel eSIM and SIM cards. We offer affordable, hassle-free plans with options for data-only or data with calls and SMS, covering 200+ destinations. Order our prepaid SIM cards online for fast delivery to your doorstep, or choose an eSIM for instant purchase and easy activation. With our unmatched coverage and award-winning customer support, you can explore the world with confidence wherever your travels take you.
How does SimCorner's service work?
Order your travel SIM online and select the delivery method that best suits your travel date. SimCorner delivers to many countries across the world and has dispatch locations in Australia, Canada, New Zealand and United Kingdom.
Receive your Japan SIM card in the mail prior to departing for your trip.
Insert your Japan SIM card in your phone as soon as you land and stay connected.
What do I need to do before I depart?
Make sure that your device is unlocked before you depart for your trip.
Please note: Being on a post-paid plan or contract with your local carrier doesn't mean your phone is locked. If you are unsure, please check with your current service provider.
What will my phone number be?
This is a data only SIM. It does not come with a phone number.
How do I check my Data balance/allowances?
You can keep track of your Data usage through your phone's data usage function (found in Settings).
Can I hotspot/tether from your phone?
Yes, you are able to hotspot/tether from your phone to another phone or device. The total hotspot limits vary by plan; they are noted below:
15 days – 15GB 31 days – 30GBWhich country(ies) does this Japan SIM work in?
Japan
What settings do I need to change/update to use this Japan SIM?
Once the SIM is loaded, you simply need to have both MOBILE DATA and DATA ROAMING functions ENABLED/TURNED ON in your phone to use the service. If you face issues, then you might need to update the APN Setting in your device as noted in the booklet.
What is the data APN settings for this Japan SIM card?
The mobile data APN settings should automatically update when you insert the sim in you phone. If it does not, you need to update the settings as noted in the instructions provided.
Which carrier(s) does this Japan SIM card connect to?
This SIM connects to the KDDI au network in Japan.
How many days is this Japan SIM card valid for?
Depends on the SIM purchased you can either have 15 days or 31 days of service. Your days of service will start when the SIM is connected to a network. This will be the day that your service commences.
What happens if I am travelling for longer than 31 Days?
If you are travelling for longer than 31 days, please purchase multiple sims accordingly. For example, if you are travelling for 45 days then purchase 2 of these sims and swap them over at the end of the 31 day period.
How do I recharge this Japan SIM card?
This sim cannot be recharged. Please ensure you purchase the correct duration based on how long your trip is for. Your days of service will start when the SIM is connected to a network in Japan. This will be the day that your service commences.
What happens if I have trouble with the eSIM?
Should you run into any issues with the eSIM whilst overseas then we encourage you to email us immediately at support@simcorner.com and let us know the following information;
Your order number or the name that the order is under Which country you are in currently and whether the eSIM connects to any network, if so, which network? Did you receive any SMS after you installed the eSIM. If so, please send us a screenshot of that message. Message us screenshots of any error message you are getting. What phone model you are using? Any other information about the issue, which will assist us in helping you resolve the issue.What if I have trouble using my data?
Should you run into any issues with the sim whilst overseas then we encourage you to email us immediately at support@simcorner.com and let us know the following information;
Your order number or the name that the order is under along with the SIM number and phone number. Which country you are in currently and whether the sim connects to any network, if so, which network? Did you receive any SMS after you inserted the sim? If so, please send us a screenshot of that message. Message us screenshots of any error message you are getting. What phone model you are using? Any other information about the issue, which will assist us in helping you resolve the issue.How do I make calls and send SMS?
You are not able to send SMS and make phones calls with this Japan SIM Card. We recommend that you use data based apps such as Whatsapp, Viber, Skype to send messages to friends and family.
How do my family and friends call and message me?
You can stay in touch with your family and friends by sending them messages and calling them via data based apps such as Whatsapp, Viber, Snapchat, Messenger, Skype, iMessage etc.
You are also able to add credit to your Viber or Skype account, which will allow you to make local and international phone calls directly to landlines and mobiles.
If I buy two Japan SIM cards (one for myself and my partner) can we contact each other?
Yes, if you purchase 2 Japan SIM cards then you will be able to contact each other via data based apps such as Whatsapp, Viber, Snapchat, Messenger, Skype etc.
I am travelling with my friends and family, how do I contact them?
You can stay in touch with your family and friends by sending them messages and calling them via data based apps such as Whatsapp, Viber, Snapchat, Messenger, Skype, iMessage etc.
You are also able to add credit to your Viber or Skype account, which will allow you to make local and international phone calls directly to landlines and mobiles.
What is your refund policy?
We have a 100% Money Back Guarantee policy, which means that if you have a bad experience with one of our sim card and receive no value from it, we will provide you a refund. However, you MUST contact us whilst you are having the issue, so our team can assist you in resolving your problems. Please do this when you are in WiFi (generally at the airport when you land if not working to begin with) or e-mail us from your accommodations (WiFi) or cafe etc. If you only decide to contact us after you return to let us know the sim didn't work then we can't look to provide a refund as we won't be able to see exactly what the issue was and why it didn't work.
Should you run into any issues whilst using the sim card, please immediately contact us at support@simcorner.com Should our team be unable to assist you in resolving your issue, then we will provide you a refund on your purchase.
Will I still have access to all my apps, messages, contacts and e-mails?
Yes, you will have access to all your apps, messages, contacts and emails whilst using this Japan SIM card. Nothing on your phone is deleted or changed and you can continue to use your phone as per normal.
Real people. Real support.
SimCorner ensures a 24/7 human customer helpline, so you can travel to every corner of the world. Our dedicated team is always on board to resolve your queries.
We're here. Anytime. Just a click away.
Travel Guide
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