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By
Clay Thomas
If you are traveling to Japan and use your phone heavily, you are probably looking for an unlimited data eSIM so you do not have to keep checking how many gigabytes you have left, buy additional data halfway through your trip, or worry about running out when you need maps, translations, train information, or reservations.
But "unlimited data" does not always mean unlimited high-speed data. In fact, the unlimited Japan eSIM plans currently available generally fall into three categories:
Truly unlimited: These plans have no daily high-speed data allowance and no usage-based throttling, so your speeds stay consistent no matter how much data you use.
Unlimited with a daily high-speed allowance: These plans give you a set amount of full-speed data each day. Once you reach that allowance, you can continue using data, but at a reduced speed until the allowance resets.
Unlimited with an undisclosed fair usage policy: These plans advertise unlimited data but apply a fair usage policy (FUP) without clearly stating how much data you can use before your speeds may be reduced.
Most unlimited Japan eSIMs from the big international providers fall into the second and third categories. That means eSIMs advertised as "unlimited" can offer very different experiences, particularly if you plan to stream video, upload large files, work remotely, or use a lot of data each day.
In this guide, we'll share details about the seven best unlimited data eSIMs for Japan (including our own), their actual data restrictions, networks, hotspot allowances, pricing, and other details you should know before choosing a plan.
1. Journey Japan eSIM
Journey Japan eSIM is our own Japan-focused eSIM, built specifically for travelers visiting Japan, rather than as part of a global eSIM marketplace covering hundreds of countries.
With the Journey Japan eSIM, you get true Unlimited 5G plans that do not have a daily high-speed data allowance or usage-based throttling.
That makes it particularly useful if you expect to use a lot of data for streaming, uploading photos and videos, making video calls, working remotely, or simply do not want to keep track of how much data you have used during your trip.
Truly unlimited data with no daily high-speed cap
Some eSIM providers technically allow you to continue using data after reaching a daily limit, but only the first few gigabytes are available at normal 4G or 5G speeds. Once you reach that allowance, your connection is reduced until the next reset.
Journey Japan's True Unlimited plans do not have a daily data cap and no automatic slowdown after you use a certain amount of data.
That does not mean you will always receive the same exact speed. Like any mobile connection, actual performance can vary depending on your location, signal strength, network congestion, device, and whether 5G is available where you are.
The important distinction is that your speed is not intentionally reduced simply because you crossed a daily usage threshold.
For travelers specifically searching for an unlimited eSIM because they expect heavy data use, that is one of the most important differences to look for.
5G coverage on KDDI's network
Journey Japan's True Unlimited plans run on KDDI, one of Japan's major mobile networks, and support 5G, 4G, and LTE where available.
Our network setup provides approximately 99% data coverage across Japan, which makes it suitable for trips that extend beyond central Tokyo, Osaka, and Kyoto.
That can be especially useful if your itinerary includes regional destinations, smaller cities, rural parts, or longer train journeys where you still need access to maps, translation tools, reservations, and transport information.
Our coverage is also really strong in tunnels, mountainous areas, inside some buildings, and in locations with heavy network congestion.
7-, 15-, and 30-day True Unlimited plans
We currently offer three True Unlimited 5G options:
Plan | Current Price | Regular Price | Data |
|---|---|---|---|
$29 | $34 | True Unlimited 5G | |
$49 | $59 | True Unlimited 5G | |
$79 | $84 | True Unlimited 5G |
The 7-day plan works well for shorter trips, while the 15- and 30-day options let you keep the same eSIM active throughout a longer stay without buying additional data halfway through your trip.
Each plan also comes with a 180-day activation window, so you can purchase your eSIM well before traveling rather than waiting until just before departure.
Hotspot and tethering
Journey Japan's unlimited plans support hotspot and tethering, so you can connect another device such as a laptop or tablet when needed.
However, the hotspot allowance is separate from the unlimited mobile data available directly on your phone.
Because hotspot limits can vary by plan and current product terms, we recommend checking the latest allowance on the plan page before purchasing if tethering is an important part of how you plan to use the eSIM.
Install before your trip and connect when you arrive
After purchase, you will get the eSIM details and installation instructions electronically, so you can set it up before leaving home while you still have a reliable Wi-Fi connection.
Once you arrive in Japan, you can switch to the Journey Japan eSIM for mobile data without visiting an airport SIM counter, collecting a pocket Wi-Fi device, or replacing your physical SIM.
The True Unlimited plans have a 180-day activation window, which also gives you plenty of flexibility to purchase ahead of your trip.
Who is Journey Japan's unlimited eSIM best for?
We would primarily recommend the True Unlimited plan if you know you use a lot of mobile data or simply do not want to monitor a fixed allowance throughout your trip.
It makes the most sense for:
Travelers who frequently stream video or music
Content creators uploading photos and videos
Remote workers using cloud services or video calls
Heavy social media users
Longer trips where mobile data will be used throughout the day
Travelers who specifically want to avoid daily high-speed data limits
If you mostly need Google Maps, train schedules, Google Translate, messaging, and occasional social media, you may not need unlimited data at all. Journey Japan also offers fixed-data plans for lighter usage.
But if you are specifically looking for an unlimited Japan eSIM because you do not want your speeds reduced after using a few gigabytes each day, Journey Japan's True Unlimited plans are one of the clearest options available.
2. Sakura Mobile
Sakura Mobile is one of the few Japan eSIM providers that clearly offers truly unlimited high-speed data rather than a daily allowance followed by reduced speeds.
Its 5G Unlimited eSIM runs on the au network by KDDI and has no Fair Usage Policy or daily high-speed data limit for normal phone usage. Sakura Mobile explicitly states that the plan has no speed throttling based on how much mobile data you use.
If your device does not support 5G but supports the required KDDI LTE bands, the eSIM can also connect over 4G LTE.
Be careful when choosing the plan, however, because Sakura Mobile also has other products that work differently. Its 4G unlimited eSIM, for example, provides 3GB of high-speed data per day before reducing the connection to 200kbps. The 5G Unlimited eSIM is the one to choose if you want unrestricted high-speed usage.
With Sakura mobile, hotspot use is supported but is not unlimited. The allowance varies with the duration of your plan. A 7-day unlimited eSIM currently includes up to 6GB of hotspot data, while a 15-day plan includes up to 15GB, with larger allowances on longer plans.
Sakura also offers considerably more choice in trip duration than providers that only sell 7-, 15-, or 30-day packages, making it easier to buy a plan that closely matches the length of your stay.
Pros
Truly unlimited 5G data with no daily high-speed cap
No usage-based throttling on the 5G Unlimited plan
Uses the au/KDDI network
Wide selection of plan durations
Hotspot/tethering supported
Cons
Hotspot data is limited
Sakura sells several types of "unlimited" products, so you need to make sure you select the 5G Unlimited plan
Can be more expensive than plans with daily high-speed allowances
3. SimCorner
SimCorner's Japan Unlimited eSIM is another relatively rare plan that does not impose high-speed allowance each day.
Its Japan-specific product page states that the plan has no daily data cap and is "purely unlimited." It runs on the KDDI network, supports 4G and 5G, and is available for 4, 7, 10, 15, or 31 days.
That makes SimCorner particularly interesting because many similarly priced unlimited plans technically provide unlimited total data but throttle you after a few gigabytes each day. With the Japan SimCorner plan, there is no published usage threshold that automatically reduces your phone's data speed.
Hotspot use is more restricted. The current allowances are 3GB for four days, 6GB for seven days, 9GB for ten days, 15GB for 15 days, and 30GB for the 31-day plan.
One other detail to keep in mind is how SimCorner counts days. Its Japan plans follow Japan Standard Time, with a new plan day beginning at midnight rather than every 24 hours from activation. If you activate at 11 p.m., for example, that short period before midnight still counts as your first day.
Pros
No published daily data cap
No usage-based throttling stated for the Japan unlimited plan
KDDI 4G/5G network
Several useful trip-length options
Hotspot supported
Cons
Hotspot data is limited
Days reset at midnight JST rather than in 24-hour periods
The eSIM cannot be topped up, so you need to choose the correct duration when purchasing
4. Japan Wireless
Japan Wireless is another Japan-based provider with a 5G Unlimited eSIM on KDDI. Unlike the daily-cap plans later in our list, there is no high-speed allowance that resets every day.
However, we would not put it in exactly the same category as Journey Japan, Sakura Mobile, or SimCorner because Japan Wireless does have a Fair Usage Policy.
The company describes the plan as throttle-free during normal use but says that extremely heavy usage may be temporarily speed-managed to maintain network performance. It does not publish a specific amount of data that triggers this restriction.
If you are choosing an unlimited eSIM because you expect unusually large amounts of data usage, it is worth knowing that there is still an FUP in the terms.
Japan Wireless offers plans from as little as two days through 30 days, which is useful if your trip does not fit neatly into a standard 7-, 15-, or 30-day package. Another unusual benefit is its free Pocket WiFi backup guarantee for 5G Unlimited customers, giving travelers an additional option if they experience a connectivity problem with the eSIM.
Pros
No fixed daily 3GB or 5GB high-speed allowance
Uses KDDI's 5G network
Plans available for many different trip lengths
Hotspot supported
Free Pocket WiFi backup guarantee
Japan-based customer support
Cons
Extremely heavy usage may trigger temporary speed management
The FUP does not publish a specific usage threshold
Generally more expensive than throttled unlimited plans
5. Saily
Saily's unlimited Japan eSIM is better described as unlimited data with a generous daily high-speed allowance rather than truly unlimited high-speed data.
You receive 5GB of unrestricted-speed data each day. If you use all 5GB, you are not disconnected and do not have to purchase more data. Instead, you can continue using unlimited data at speeds of up to 1Mbps until your high-speed allowance resets.
For many travelers, that may be a perfectly reasonable compromise. Five gigabytes in a single day is a substantial amount for Google Maps, train apps, messaging, web browsing, translations, and normal social media usage. Over a 15-day trip, you could use up to 75GB at unrestricted speeds if you used the complete allowance every day.
The limitation becomes more noticeable for heavy video streaming, large cloud backups, uploading a lot of video, or other data-intensive tasks. A 1Mbps connection can still handle maps, messaging, email, and basic browsing, but it is very different from normal 4G or 5G speeds.
Saily also allows hotspot sharing, and its current Japan plan page does not list a separate tethering cap. The unlimited plan therefore makes a lot of sense for travelers who want a large amount of high-speed data each day but do not necessarily need unrestricted high-speed usage around the clock.
Pros
Generous 5GB high-speed allowance each day
Unlimited data continues after the allowance is reached
Throttled speed is up to 1Mbps rather than extremely slow 128–256kbps
5G supported where available
Hotspot sharing supported
Easy management through the Saily app
Cons
Not truly unlimited high-speed data
Speeds drop to up to 1Mbps after 5GB in a day
Less suitable for extremely heavy streaming or large uploads after the daily allowance is used
6. Airalo
Airalo is one of the largest international eSIM marketplaces and is a convenient option if you already use its app for other trips. Its Japan unlimited plans are available for 3, 5, 7, 10, 15, and 30 days, with SoftBank listed as the primary network and access to an additional network.
Like Saily, Airalo's unlimited plan is not unlimited high-speed data. You receive 3GB of high-speed data during each 24-hour period. Once you use 3GB, your connection is reduced to 1Mbps until the next allowance begins.
That daily allowance should be sufficient for many normal Japan trips, but it is considerably lower than Saily's 5GB per day. Someone streaming a lot of video, uploading large files, or working remotely could reach 3GB relatively quickly.
One useful detail is that Airalo calculates the allowance as a 24-hour period from activation, rather than resetting at midnight Japan time. Airalo also supports hotspot use, although any tethered data still contributes toward the same high-speed usage allowance.
Airalo therefore makes the most sense if you value its established app and global coverage and do not expect to regularly exceed 3GB of high-speed usage each day. If unlimited high-speed data is the reason you are choosing an unlimited plan in the first place, there are better options higher on this list.
Pros
Large, established international eSIM provider
Plans from 3 to 30 days
3GB of high-speed data every 24 hours
Unlimited data continues at 1Mbps afterward
Hotspot supported
Convenient if you already use Airalo in other countries
Cons
Not truly unlimited high-speed data
High-speed allowance is only 3GB per 24 hours
Heavy users may experience throttling regularly
7. Holafly
Holafly is one of the most recognizable unlimited eSIM providers and offers a particularly flexible Japan plan.
Instead of choosing only from a few fixed durations, you can purchase an eSIM for anywhere from 1 to 90 days, which is useful for trips that do not fit into standard one-week, two-week, or one-month packages.
The important difference is how Holafly defines unlimited data. Unlike Airalo or Saily, there is no published daily high-speed allowance such as 3GB or 5GB. However, Holafly states that local network operators may apply a Fair Usage Policy after heavy high-speed usage.
If this happens, speeds can be temporarily reduced before returning to normal the following day. Holafly does not publish the amount of Japan data that triggers this restriction.
That puts Holafly in the third category of unlimited plans we described at the beginning of this guide. You will not run out of data, but you also do not know exactly how much high-speed usage you can have before network management could potentially apply.
Hotspot usage is much clearer. Holafly allows you to share 1GB per day with other devices. A 7-day plan therefore provides 7GB of total shareable data, while a 15-day plan provides 15GB.
Current prices include $27.50 for seven days, $50.50 for 15 days, and $73.90 for 30 days, although the ability to choose your exact trip length is probably a bigger reason to consider Holafly than the price itself.
Holafly can work well if you want a simple unlimited plan and the freedom to choose the exact number of days you need. For travelers expecting extremely heavy usage, though, we would prefer an unlimited provider that clearly states whether there is a usage threshold or throttling policy.
Pros
Choose anywhere from 1 to 90 days
No fixed amount of total data
5G/4G connectivity
1GB of hotspot data per day
24/7 customer support
Simple app and installation process
Cons
Fair Usage Policy can result in temporary throttling
Holafly does not disclose the amount of data that triggers the FUP in Japan
Hotspot limited to 1GB per day
Heavy users cannot know exactly how much unrestricted high-speed data they will receive
Do You Need an Unlimited eSIM for Japan?
If you mainly use your phone for Google Maps, Google Translate, train schedules, messaging, browsing, and occasional social media, a fixed-data plan may be more than enough for your trip.
The amount you need will depend on your trip length and how much data you typically use in Japan. Unlimited data makes more sense if you expect to use your phone heavily throughout the day. That may include:
Streaming YouTube, Netflix, or other video regularly
Uploading large numbers of photos or videos
Using Instagram, TikTok, or other data-heavy social apps frequently
Working remotely while traveling
Making regular video calls
Using cloud storage or transferring large files
Traveling for several weeks and not wanting to monitor your remaining data
Simply preferring the convenience of knowing you will not run out
If you regularly use more than 3GB or 5GB in a day, a plan with a daily high-speed allowance could still slow you down even though it is advertised as unlimited. In that case, a truly unlimited plan without a daily high-speed cap may be a better fit.
You should also pay attention to hotspot and tethering limits if you plan to connect a laptop, tablet, or another device. Unlimited mobile data does not always mean unlimited hotspot data, and several providers place separate limits on how much data you can share even when usage directly on your phone is unlimited.
For most tourists, a generous fixed-data plan can still be enough. But if you are a heavy user, plan to work during your trip, stream frequently, or simply do not want to think about how much data you have left each day, an unlimited eSIM can make staying connected in Japan much easier.
Get Unlimited Data for Your Trip to Japan
There are now plenty of Japan eSIMs advertised as unlimited, but as the plans above show, the word can mean very different things from one provider to another.
Some plans give you only a few gigabytes of high-speed data each day before reducing your connection. Others apply an undisclosed Fair Usage Policy, which makes it difficult to know exactly how much high-speed data you can use. If you expect heavy usage, checking those restrictions is just as important as comparing price, network coverage, or trip duration.
Journey Japan's True Unlimited 5G eSIM is designed for travelers who do not want a daily high-speed data cap. It runs on KDDI's network, supports 5G where available, and does not automatically reduce your speeds after you use a certain number of gigabytes.
If you would rather spend your trip using your data than checking how much of it you have left, you can choose a Journey Japan True Unlimited eSIM based on the length of your stay.
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