1What Is a Travel eSIM?

An eSIM (Embedded SIM) is a virtual SIM card built directly into your phone's chip. Instead of swapping a physical card, you activate it by scanning a QR code or downloading a profile — that's it. For travellers, the key advantages are:

• Buy and install before you leave home; arrive in Japan and you're immediately online
• Keep your home SIM in the phone to receive SMS verification codes while abroad
• Most plans offer large or unlimited data — ideal for heavy smartphone users
• No airport queues, no vending machines, no physical SIM to lose

eSIM is supported on iPhone XS and later, and most flagship Android devices released after 2018. To check: go to Settings → Mobile / Cellular — if you see an "eSIM" or "Add Plan" option, you're good to go.

2How to Choose the Right Japan eSIM Provider

The market is crowded and quality varies enormously. Here's how the most popular providers stack up:

3Traffic Routing & Privacy

Many travel eSIM providers — Holafly being the most-cited example — route your data through relay servers in Singapore, Hong Kong, or Poland rather than connecting directly to Japan's network. This creates three concrete problems:

• Your IP address shows as Singapore, locking you out of Japanese banking apps and region-locked streaming (e.g. Netflix Japan)
• The extra routing hop adds latency, making your connection noticeably slower
• Your browsing data passes through a third-party server, creating a genuine privacy risk

Already bought an eSIM with routing problems? Three fixes

Option 1 (fastest): Use a VPN — Connect to a Japanese server to obtain a Japanese IP. The downside is further speed reduction and higher data usage.

Option 2 (most reliable): Add a local eSIM — Pick up a CDJapan local eSIM and switch to it whenever you need a genuine Japanese IP. Faster than a VPN and no extra app required.

Option 3: Request a refund and switch providers — If the provider did not clearly disclose their routing method before purchase, you have grounds to dispute the charge and move to a local-routing provider.

Privacy tips for daily use

• Only browse sites with HTTPS (look for the padlock in the address bar)
• Disable GPS and location sharing unless you actively need it
• Use Firefox or Brave instead of Chrome for better privacy defaults
• Turn off "Ad Tracking" and "Analytics Data Sharing" in your phone's settings

4Device Compatibility

Before purchasing, confirm two things: that your phone supports eSIM, and that it isn't carrier-locked.

Google Pixel 9 / 10 users: important warning

A large number of Pixel 9 and Pixel 10 users have reported that Ubigi eSIMs fail to connect in Japan. The root cause is that Japan-market versions of these devices are carrier-locked to Japanese operators, which conflicts with Ubigi's network authentication process.

If your phone is carrier-locked, contact your home operator at least two weeks before departure to request an unlock. You'll need your IMEI number (dial *#06# to find it). Most carriers complete unlocks within 24–48 hours.

5Fixing Common Activation Issues

Even a successfully installed eSIM can show "No Network" or refuse to connect after you land. Here are the most common causes and how to fix them:

Step 1: Check your data roaming setting

This is the most frequently overlooked step. Roaming-type eSIMs (e.g. Airalo) require data roaming to be turned ON, while local Japan eSIMs (e.g. CDJapan) require data roaming to be turned OFF:

• iOS: Settings → Mobile Service → Mobile Data → Data Roaming → On / Off
• Android: Settings → Mobile Network → Roaming → On / Off

Step 2: Set the eSIM as your default data line

• iOS: Settings → Mobile Service → select your eSIM plan as "Primary"
• Android: Settings → SIM Cards & Mobile Networks → select eSIM as "Default data SIM"

Step 3: Wait 5–15 minutes for activation to complete

Be patient and resist the urge to keep restarting your phone. Your carrier name (e.g. "NTT Docomo") should eventually appear in the status bar.

Still not connecting? Advanced fixes

1. Manually configure APN (Android): Go to Settings → Mobile Network → Advanced → APN and enter the details provided by your eSIM provider.
2. Restart your phone: Power off for 30 seconds, then back on. This resets the network stack and often resolves the issue.
3. Reinstall the eSIM: Some eSIMs support reinstallation — confirm with your provider first. Delete the profile, then scan the backup QR code again.
4. Contact support: Share your phone model and IMEI with the provider's support team. Most issues are resolved within 1–2 hours.