Check what your home carrier includes first. If you need a separate data plan and your phone is unlocked and eSIM-compatible, you can set one up over Wi-Fi before you fly.
Compare the same plan size
These examples are Japan-only, one-time data plans with 10 GB over 30 days. Listed prices in US dollars were checked . Your price and currency may differ at checkout. Comparison is based on provider documentation. Scroll the table on a small screen to read all columns.
Start with your phone’s recent mobile data usage and your trip length. Maps, messaging and occasional browsing use less data than streaming, video calls or laptop tethering. Download maps over Wi-Fi, pause mobile photo backups and check top-up costs before buying.
On an unlimited plan, look for the high-speed allowance and the speed after it runs out. Compare by trip length and what you can do at the reduced speed. The Saily Japan unlimited plan currently lists a daily high-speed allowance and a lower speed afterward.
Will I have a phone number?
The plans in the table provide mobile data for maps, browsers and internet calling apps. If you need a Japanese number for regular calls or texts, choose a plan that explicitly includes one. Sakura Mobile offers a visitor voice-and-data plan that requires in-person ID verification.
Saily’s optional number is US-based. If you rely on bank codes sent to your existing number, check your home carrier’s Japan roaming terms and set up a backup sign-in method before departure.
Check the exact device. Verify eSIM support for your model and market and confirm the phone is unlocked. On iPhone, open Settings → General → About and look for “No SIM Restrictions” under Carrier Lock. For Android, check with the manufacturer and your carrier.
Buy for the places and dates you need. Check the local network and the activation window. A Japan-only plan starts working in its coverage area. For a stopover, check whether your regional plan covers that country too.
Prepare on reliable Wi-Fi. Install before departure if the plan’s validity starts on connection. If installation starts the clock, wait until closer to arrival. Keep your receipt and setup instructions somewhere you can open offline, and keep the installation QR code private.
Select the travel line for mobile data. Turn it on and follow its roaming instructions. Disable automatic mobile-data switching and keep data roaming off on the home line unless you intend to use it. Calls and texts on your home line can still incur carrier charges.
Test before leaving the terminal. With Wi-Fi briefly off, open a web page. If it fails, check the selected data line, the eSIM’s roaming setting and any provider-specific APN. Rejoin airport Wi-Fi to contact support before deleting the profile. Some profiles cannot be installed twice.
Keep another way to get online. If your phone is locked or you need one connection for several devices, consider pocket Wi-Fi and check the pickup and return hours. If your phone is unlocked and has a SIM tray, a compatible physical SIM is another option. Save the first-trip connectivity checklist for maps and hotel directions.