eSIM Users Beware! When & Where Speed Slows Down in Japan
Updated : 2025-02-07 15:44:39
If you're planning a trip to Japan, you might be considering portable Wi-Fi for internet access, but "eSIM" has also become very popular recently. An eSIM is a convenient way to stay connected because it doesn’t require swapping a physical SIM card and can be installed directly on your smartphone.
Compared to portable Wi-Fi, eSIM offers:
- No need to carry a device (no worries about losing or charging it)
- Easy setup (just scan a QR code)
- No need to return the device
eSIM vs. Pocket WiFi: Which is better for traveling in Japan?
To use eSIM smoothly in Japan, it's important to understand when and where internet speeds tend to slow down. This article explains the factors that can cause slow internet during your trip.
Preparing to Use eSIM in Japan
1. Check if Your Smartphone Supports eSIM
First, make sure your smartphone is compatible with eSIM.
How to Quickly Check if Your Smartphone Can Use a Japanese eSIM in 5 Seconds
2. Purchase and Set Up Your eSIM in Advance
It's better to buy and set up your eSIM before arriving in Japan. Doing so ensures a smooth experience once you land.
3. Choose the Right Carrier or Provider
Several eSIM providers offer services in Japan, each with different plans and pricing. If you're staying for a short period, a prepaid plan is recommended.
Travel Mobile offers eSIMs that work in Japan
Our eSIMs use Japan’s largest network, docomo, and provide large data capacity. If you are traveling to Japan, consider using Travel Mobile’s eSIM.eSIM Japan
Times When Internet Speed Slows Down in Japan
1. Weekday Evenings (8:00 PM - 12:00 AM)
- Internet usage increases at night, especially between 8:00 PM and 12:00 AM, leading to network congestion.
- Due to the way internet connections work, speeds can drop significantly.
- The evening commute (5:00 PM - 7:00 PM) is another peak time, as many people use their smartphones on trains.
2. Lunchtime on Weekdays (12:00 PM - 1:00 PM)
- During office and school lunch breaks, employees and students use their smartphones for streaming and social media, slowing down the internet.
3. Weekend Afternoons (2:00 PM - 5:00 PM)
- In shopping malls and tourist spots, a large number of people using the internet can cause congestion.
Even if the internet speed slows down, it doesn't mean you won't be able to do anything. You will still have enough speed to send messages, browse social media, and view websites.
Places Where Internet Speed Slows Down
To make it easier to understand, it can be roughly categorized as follows.| Location | Reason for Slow Speed |
|---|---|
| Trains & Stations | Too many people connected |
| Event Venues | High concentration of users |
| Underground | Signal reflection & loss |
| Mountain Areas | Few cell towers available |
| Concrete Buildings | Structural interference |
| Busy Tourist Areas | Increased network traffic |
Shinkansen (bullet train)
When traveling on the Shinkansen (bullet train), the internet can slow down due to:- Weak signals in mountainous areas
- High numbers of passengers using the network at the same time
The Shinkansen carries a large number of passengers, and in mountain tunnels, internet speed drops significantly.
Estimated Internet Speed for eSIM and Prepaid SIM Cards During Peak Hours
Speed During Peak Hours (Day & Night)
Daytime (12:00 PM - 1:00 PM)
Average download speed: Around 5 to 36 Mbps.
Some services may slow down further, reaching around 1 Mbps.
Nighttime (7:00 PM - 10:00 PM)
Average download speed: Around 10 to 56 Mbps.
Although speeds improve at night compared to daytime, they can drop below 10 Mbps if many users are connected.
Comfortable Internet Speed Guide
General Speed Reference
| Download Speed | 5 - 30 Mbps |
| Upload Speed | 1 - 10 Mbps |
Recommended Speed by Usage
| Web Browsing & Social Media | 3 - 5 Mbps |
| Video Streaming (Standard Quality) | 5 Mbps or higher |
| Video Streaming (High Quality) | 25 Mbps or higher |
Many plans still offer around 5 Mbps even during peak hours, so browsing websites and using social media should not be a problem.
What You Can’t Do When the Internet Is Slow & How to Cope
Problems with Slow Internet
- Streaming videos (YouTube, Netflix, etc.)
- Video calls (Zoom, LINE, etc.)
- Downloading large files
Solutions for Slow Internet
- Move to a less crowded area (avoid congested places)
- Use public Wi-Fi (cafes, hotels, etc.)
- Download videos and maps in advance
- Enable data-saving features (use a browser's lightweight mode)
eSIM is a very convenient option for traveling in Japan, but understanding Japan's unique internet situation is essential.
Internet speeds slow down during night (8:00 PM - 12:00 AM),"lunchtime (12:00 PM - 1:00 PM), and weekend afternoons (2:00 PM - 5:00 PM).
Slow locations include trains & stations, event venues, underground, mountain areas, and busy tourist spots.
Even if you encounter slow internet speeds at certain times or places, you will still have enough speed to browse social media or send messages on your smartphone. So, for most people, it may not be a big issue. However, if you need to search for information or shop online, try to do so when you are not in a crowded area.
By keeping these tips in mind, you can enjoy a smooth and stress-free trip to Japan!