Best eSIM for Japan: Docomo, SoftBank or KDDI?

Japan's three carriers — NTT Docomo, SoftBank, and KDDI (au) — all cover the populated areas well. The differences show up in the mountains, the JR rail tunnels, and the smaller islands. If you're sticking to Tokyo / Kyoto / Osaka and the train lines between them, network choice barely matters.

Recommended providers

• Airalo Japan Moshi Moshi — 7 days, 10 GB, ~$15. Routes through SoftBank.
• Holafly Japan — 7 days unlimited, $33. Docomo backbone.
• Ubigi Japan — best 5G coverage; pricier.

If you'll be in rural Hokkaido or Tohoku, prefer Docomo-backed plans — they have more cell sites outside city centers.

Stuff that surprises people

• Pocket WiFi is dying. It's still rented at Narita and Haneda but the price-per-GB is now worse than eSIMs, and you have to lug another device.
• JR Pass and IC cards have moved to eSIM-enabled apps. A working data line in your phone replaces the kiosks for most things.
• Free WiFi is not great. "Japan Free Wi-Fi" hotspots work in stations and convenience stores but auth is fiddly. Don't rely on it.

What to do before you fly

1. Buy the eSIM 1–2 days before departure (most activate on first network attach, not at purchase).
2. Save the QR / activation code somewhere offline.
3. On the plane, install the profile but leave it disabled.
4. After landing, switch your data line to the new profile.
5. Keep your home line on, data off, so SMS 2FA still works.

That's it. By the time you're at the JR ticket gate, you'll have a 5G connection.