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Hidden Secret of Throttling & Data Cap of Pocket WiFi in Japan

“Unlimited”, “all you can”, “no strings attached”, surely these phrases are a marketers best friend when it comes to advertising a product. Every consumer wants as much for their money as they can possibly get. Companies know this fact, and they use key marketing wordings to prey on customers desires. Companies providing Pocket WiFi rental service in Japan are no exception.

One of the most popular questions that customers have when renting a Pocket WiFi device is, “is there a data cap?”. The answer to this question is actually a little more complicated than just yes or no. And it can be even more confusing when companies are prone to using the word “Unlimited” when referring to a plan’s data limits.

In general, Pocket WiFi rental companies tend to advertise their service or products in the best light possible while doing whatever they can to avoid that which could highlight something negative about their service like a data cap. What is the truth? Let’s look into it.

Throttling and Fair Usage Policy

Fair Usage Policy is a policy put in place that is designed to prevent one user on a network from monopolizing all the internet traffic from the rest of the users, for example, by constantly downloading large files. The network provider will then slow or stop that user’s internet connection. In other words, fair use limits the data usage of one user over others at times of peak traffic in order to ensure that, for the rest of the group, performance is not affected. For more on this check out one of our articles that takes an in-depth dive into fair usage policy and its effects on Pocket WiFi rental.

The mechanism by which fair usage policies ensure this data fairness among users is referred to as data throttling (also known as bandwidth throttling or internet bottleneck). Throttling is the process in which an ISP (internet service provider) willfully limits a user’s bandwidth, which in turn slows down download and connection speeds.

Let’s make this clear right away. Almost all Pocket WiFi rental companies’ WiFi products are subjected to throttling no matter what the company may be claiming. That fair usage policy is put in place for that very reason. And the subsequent throttling will slow your connection once you reach a certain data use limit. So although it may be true that you can use data indefinitely, that indefinite data will not be at the speed prior to the throttling.

Also, another important misconception to clear up is that many of these companies talk about a daily limit. However, most of the Pocket WiFi rental companies in Japan are using mobile routers provided by the cellular company SoftBank, and come with a predetermined total or monthly data cap. So you should base your thinking on data use around that total data allotment rather than a daily data cap.

Throttling and Internet Speed

Okay, so we have established that the potential for throttling exists in almost all Pocket WiFi rental contracts. But what is the actual effect on data speed?

Once throttling begins data speeds will fall under 100kbps for both download and upload speeds. These extremely low speeds will make it difficult for you to anything on the internet besides basic functions like checking emails and google searches. At these speeds, streaming music or videos and high data-use activities like downloading apps will be out of the question. Even loading webpages with multiple images will become substantially slower.

Frustrating when internet is slow... right?

Evidences that throttling may occur

Since throttling is a result of fair usage policies, in order to know if your data may be capped, you have to first find the info on the companies’ website. Most of these WiFi rental companies put the information regarding their fair usage policies in very fine print that may be hard to spot with the untrained eye. Let's take a look at some of these company's websites for reference.

The websites usually keep the information under their FAQ or Spec sections.


One of the services this company offers has its policy under the site’s data usage guidelines. As you can see below this policy states pretty explicitly that if the company detects a user using an excessive amount of data they have the right to not only lower but even disconnect your connection speed. With no notification.


This company keeps its information on the policy under their FAQ, Transition Speed Limit section. As you can see below, it states that if your data usage in a set period exceeds the capacity limit, they will enact their transmission speed limit thereby slowing your connection speed.


NinjaWiFi is one of the bigger players we’ve covered in a couple of our other comparison articles. These guys also claim their data is "Unlimited" However, under the subsection below, It says, due to what they refer to as their "best effort system", that data transmission rates can be subject to slowing or even have no connectivity entirely. (That sounds like a data cap if you ask me.)


Flypack's fair usage policy info is written under FAQs, Fair Usage Policy (FUP). This policy states that the carrier reserves the right, without any notice or limitations to slow or terminate internet service to any user, based on what they deem as unfair or excessive usage.


KKday's info is under their Important booking information section. This section just has one line that states its policy on data usage. It says, that if you excessively consume data it may result in slower or weaker signal reception.

And this is just the tip of the iceberg! There are plenty more examples of this at just about every Pocket WiFi company out there.

Consider personal data needs!

As you can see from the examples above and to repeat what was said at the beginning of the article, because of Fair Usage Policy, a data cap does exist for almost all Pocket WiFi devices in Japan and therefore will experience throttling / speed reduction after you exceed a certain data usage.

However, this needs to be taken with a grain of salt. Data throttling is most likely a non-issue for a normal traveler. A typical Pocket WiFi device from most companies will provide an average traveler with enough data to get comfortably through their stay in Japan.

That said, high data-use activities like streaming videos, large file sharing, photo/video sync, etc., is something that may pose an issue. So if you know you will need a lot of data for these high data-use activities, let’s say you’re a YouTuber or you’re traveling with a large group or you use the internet frequently and variedly for work, you should be particularly careful.

Either way, we advise that you avoid companies that use per day data caps or just say unlimited, and go with a company that tells you how much data you can use at high speeds for the whole rental period.

At eConnect Japan, we have multiple Pocket WiFi rental plans that will suit every type of user. We also tell you from the get-go exactly what your data limit will be so you will be able to better asses which plan is right for your data needs.

Feel free to visit our website 👇 and check out our affordable Pocket WiFi rental service for your trip to Japan!

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