What you’ll learn in this article
- Differences between Unlimited and Data-Limited SIMs
- Advantages and Disadvantages of Each
- Common Failure Patterns in Japan Travel
- Recommendations by Travel Style
- How to Choose a SIM or eSIM
Conclusion: “Data-Limited SIMs” Offer Better Cost Performance for Most Travelers
For SIMs used for traveling in Japan,
a “data-limited SIM (5GB to 10GB)” is a cost-effective and less risky choice for most travelers.
The reason is that smartphone usage during travel in Japan is
concentrated on light to moderate communication such as maps, searches, and SNS.
If you want to check how to choose a SIM from the beginning,
please also refer to Recommended SIMs and How to Choose for Travelers to Japan [2026 Latest Edition].
What is an Unlimited SIM?
An unlimited SIM is
a SIM plan that allows you to use data without worrying about the data limit for a certain period of time.
However, it is not “completely unlimited,” and
in many cases, there are the following restrictions:
- Speed restrictions apply after exceeding a certain amount
- Communication speed slows down during crowded times
- Tethering may be restricted
It is convenient for people who watch a lot of videos, but
it can be expensive depending on how you use it.
What is a Data-Limited SIM?
A data-limited SIM is
a type that uses a predetermined amount of data (e.g., 5GB, 10GB).
The features are as follows:
- Low price and easy-to-understand plan
- Stable communication speeds
- Easy to choose according to your usage
Most people choose this data-limited SIM for traveling in Japan.
Who is an Unlimited SIM for?
Unlimited SIMs are suitable for the following people:
- Frequently watch YouTube and Netflix while traveling
- Also use a PC/tablet for tethering
- Don’t want to worry about data usage at all
- Itinerary with a lot of long-distance travel
It gives you a sense of security, but
it tends to be overkill for people who don’t use it.
Who is a Data-Limited SIM for?
Data-limited SIMs are ideal for the following travelers:
- Mainly use Google Maps, search, and SNS
- Also use Wi-Fi in hotels and cafes
- Want to keep communication costs as low as possible
- First time traveling to Japan
For more information on the required data amount,
please see How much SIM data is required for traveling in Japan? [2026 Edition] for details.
Common Failure Examples with Unlimited SIMs
This is a common failure for travelers who choose an unlimited SIM.
- The speed is slow even though it is “unlimited,” making it difficult to watch videos
- The price was higher than expected
- Trouble because tethering was not possible
- I didn’t actually use that much data
“Unlimited for the time being” is not always the correct answer.
In Japan travel, “data-limited with a little extra” is just right
In Japan travel,
- Little smartphone use for sightseeing during the day
- Hotel Wi-Fi is available at night
- Good communication environment in subways and major areas
In many cases,
a 5GB to 10GB data-limited SIM is usually sufficient.
The selection method is the same for both SIM cards and eSIMs
The concept of unlimited/data-limited is
- Physical SIM card
- eSIM
Common to both.
For information on the features and how to choose an eSIM, please refer to
Recommended eSIMs and How to Choose for Travelers to Japan [2026 Latest Edition].
Summary: If you’re not sure, start by considering a “data-limited SIM”
- A data-limited SIM is sufficient for most travelers
- Unlimited SIMs are for those who use videos and tethering a lot
- 5GB to 10GB is a guideline for traveling in Japan
- The most important thing is to choose according to your usage
For the final plan selection,
we recommend checking by usage on the SIM list/comparison page for travelers.
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