Short answer
When a Japan eSIM runs out of data, the Japan plan page states the result on the row named At your data limit, and your account shows the remaining reading when it has one. The phone's data screen counts data the phone has used, and the Japan eSIM guide is where Wakamo explains a top-up.
Fixed plans, day passes, and whether that plan can be topped up are covered in How do fixed-data Japan eSIM plans, day passes, and top-ups differ?.
Fact table
As of 2026-10-21
Each claim names its source. The full source list, with the date each page was read, is below.
| Claim | Source |
|---|---|
| On the Japan plan page, each plan has a row named At your data limit. That row is where the page states what happens for that plan. | Wakamo Japan plan page |
| Wakamo help says to open My eSIMs using the account you bought with. Usage can take time to update, and help says to check when it was last refreshed. | Wakamo help |
| When a usage reading exists, the account labels it Last known usage and shows how much is remaining. If the reading is missing, the account says Usage unavailable. A stale reading says Usage may be out of date. | Wakamo account |
| The Japan eSIM guide is where Wakamo explains top-ups for a Japan plan. | Wakamo Japan eSIM guide |
| On iPhone, Apple says to go to the Settings app and tap Cellular. To see how much data each app is using, scroll down and tap Show All. The amount of cellular data used appears below each app. With Dual SIM, that is how much data you have used with the selected cellular data number. Reset Statistics is at the bottom of Cellular. Apple says to contact your carrier for the most accurate cellular data usage from a current period. | Apple Support, iPhone cellular data |
| If cellular data is off, Apple says all data services, including email, web browsing, and notifications, use Wi-Fi only. | Apple Support, iPhone cellular data |
| On a Pixel, Google says to open Settings, tap Network & internet, then SIMs. The total mobile data used is at the top. Google says the phone measures the data usage shown in Settings, some carriers measure differently, and to check with the carrier for its measurements and your plan limits. Some of these steps work only on Android 8.0 and up. If the steps do not match the phone, Google says to check with the device manufacturer. | Pixel Help, mobile data usage |
| On a Pixel, a data warning you set sends a notification when usage reaches the level you picked. A data limit you set turns mobile data off and sends a notification. Turning off Set data limit turns mobile data back on. Google says some features will not work when mobile data is turned off. | Pixel Help, mobile data usage |
| Samsung says a Galaxy phone tracks how much mobile data you use each month, and that this gives a good idea of how much you have used and how much you have left. Samsung also says the tracker is an estimate for a monthly cycle, the allowance comes from the network operator, and a smartphone cannot automatically recognise how much data you have to use each month. You compare the amount used in the billing cycle with that allowance. For a day or a week, Samsung says to contact the network operator. | Samsung, Galaxy data usage |
| Samsung says the tracker runs from the start of the month to the end unless you set the start date to the date the network operator refreshes the allowance. After a new start date, Samsung says it can take up to a month to reflect usage more accurately. A data warning notifies you at an amount you choose. A data limit you set turns mobile data off at the amount you choose. The path is Settings, then Connections, then Data usage. | Samsung, Galaxy data usage |
FAQ
What happens when a Japan eSIM runs out of data?
On the Japan plan page, each plan has a row named At your data limit. That row is where the page states what happens for that plan.
How do I check how much data is left?
Wakamo help says to open My eSIMs using the account you bought with. Usage can take time to update, and help says to check when it was last refreshed. When a usage reading exists, the account labels it Last known usage and shows how much is remaining. If the reading is missing, the account says Usage unavailable. A stale reading says Usage may be out of date.
Does the phone show the data left on the eSIM?
Samsung says a smartphone cannot automatically recognise how much data you have to use each month. You compare the amount used in the billing cycle with that allowance. The Galaxy tracker is an estimate for a monthly cycle, and Samsung says it gives a good idea of how much you have used and how much you have left. Apple says to contact your carrier for the most accurate cellular data usage from a current period. Google says the phone measures the data usage shown in Settings, some carriers measure differently, and to check with the carrier for its measurements and your plan limits.
How do I see usage on an iPhone?
On iPhone, Apple says to go to the Settings app and tap Cellular. To see how much data each app is using, scroll down and tap Show All. The amount of cellular data used appears below each app. With Dual SIM, that is how much data you have used with the selected cellular data number. Reset Statistics is at the bottom of Cellular. Apple says to contact your carrier for the most accurate cellular data usage from a current period. If cellular data is off, Apple says all data services, including email, web browsing, and notifications, use Wi-Fi only.
How do I see usage on a Pixel or a Galaxy phone?
On a Pixel, Google says to open Settings, tap Network & internet, then SIMs. The total mobile data used is at the top. Some of these steps work only on Android 8.0 and up. If the steps do not match the phone, Google says to check with the device manufacturer. On a Galaxy phone, the path is Settings, then Connections, then Data usage. Samsung says the tracker runs from the start of the month to the end unless you set the start date to the date the network operator refreshes the allowance. For a day or a week, Samsung says to contact the network operator.
What does a data limit on the phone do?
On a Pixel, a data warning you set sends a notification when usage reaches the level you picked. A data limit you set turns mobile data off and sends a notification. Turning off Set data limit turns mobile data back on. Google says some features will not work when mobile data is turned off. On a Galaxy phone, a data warning notifies you at an amount you choose, and a data limit you set turns mobile data off at the amount you choose. If cellular data is off, Apple says all data services, including email, web browsing, and notifications, use Wi-Fi only.
Where do I read how to top up?
The Japan eSIM guide is where Wakamo explains top-ups for a Japan plan.
Sources
Wakamo Japan plan pagewakamo.io
Wakamo product information. Each plan has a row named At your data limit. That row is where the page states what happens for that plan. This answer names the row and does not restate it.
Accessed 2026-10-21.
Wakamo Japan eSIM guidewakamo.io
Wakamo product information. Top-ups for a Japan plan are explained on the Japan eSIM guide. This answer links that guide.
Accessed 2026-10-21.
Wakamo helpwakamo.io
Wakamo product information. Open My eSIMs with the account you bought with. Usage can take time to update; check when it was last refreshed.
Accessed 2026-10-21.
Wakamo accountwakamo.io
Wakamo product information. When a usage reading exists, it is labeled Last known usage and shows how much is remaining. If the reading is missing, the account says Usage unavailable. A stale reading says Usage may be out of date.
Accessed 2026-10-21.
Apple Support, iPhone cellular datasupport.apple.com
Settings, then Cellular. Show All lists cellular data used under each app. With Dual SIM, that list is for the selected cellular data number. Reset Statistics is at the bottom. For the most accurate usage from a current period, contact your carrier. If cellular data is off, email, web browsing, and notifications use Wi-Fi only.
Accessed 2026-10-21.
Pixel Help, mobile data usagesupport.google.com
Settings, then Network & internet, then SIMs, shows total mobile data used. The phone measures that figure. Some carriers measure differently, and Google says to check the carrier for its measurements and your plan limits. A data warning you set sends a notification. A data limit you set turns mobile data off. Turning Set data limit off turns mobile data back on. Some features will not work while mobile data is off. Some steps work only on Android 8.0 and up. If the steps do not match, check with the device manufacturer.
Accessed 2026-10-21.
Samsung, Galaxy data usagesamsung.com
A Galaxy phone tracks mobile data used each month and Samsung says that gives a good idea of how much is used and how much is left. The tracker is an estimate for a monthly cycle. The allowance comes from the network operator, and a smartphone cannot automatically recognise how much data you have each month. Compare usage in the billing cycle with that allowance. For a day or a week, contact the network operator. The default cycle is the calendar month. A new start date can take up to a month to reflect usage more accurately. A data warning notifies you. A data limit turns mobile data off. Path: Settings, Connections, Data usage.
Accessed 2026-10-21.