The reflex goes back a long way: for years, changing plan for a trip meant opening the SIM tray with a paperclip, carefully storing the tiny card and praying not to lose it. With an eSIM, that gesture belongs to the past. Here's why your SIM card stays exactly where it is — and the three settings that replace the paperclip.
eSIM and physical SIM: the two coexist in your phone
An eSIM is a 100% digital SIM card: it installs by scanning a QR code, without taking up the physical tray. Every eSIM-compatible phone is dual SIM: it handles two lines at once. During your trip to Japan, your usual SIM card and the PlanJapan eSIM therefore work side by side, each in its own role:
| Line | Its role in Japan |
|---|---|
| Your physical SIM — left in place | Keeps your usual number and receives your texts (bank codes, confirmations) — its data roaming is off, so it uses nothing. |
| PlanJapan eSIM | Provides all the data on the NTT docomo 4G/5G network: Google Maps, WhatsApp, social media, video calls with family. |
Your number stays yoursYour WhatsApp number, your contacts and your conversations are kept automatically. The eSIM only handles data. Do I keep my number? →
The 3 settings to make instead of removing your SIM
Removing the card serves no purpose; three quick settings, on the other hand, prevent any roaming charges and send the data to the right place:
In Settings → Mobile Data, choose the PlanJapan line as your data line and turn on its data roaming: all your data then runs on the NTT docomo network.
On your personal line, turn off “Data Roaming” (iPhone) or data roaming (Android). This is THE setting that prevents bill shock: your carrier can no longer charge you a single byte.
Once its data is off it uses nothing, but it keeps receiving your texts. Receiving a text is usually free abroad — check with your carrier.
Every screen is detailed step by step, for iPhone and Android alike, in the eSIM installation guide →
Why it's better to leave your SIM card in place
A nano-SIM is a few millimetres across. Between the plane, the hotel and the temples of Kyoto, it quickly ends up at the bottom of a bag — or on an airport carpet. Inside the phone, it's safe.
Without your SIM, no more verification codes by text: online payments, bookings, two-factor authentication. It's your usual line, still active, that saves you at the payment screen.
Once its data roaming is off, your usual line can no longer use anything: no risk of roaming charges, nothing else to do during the trip.
In short: don't touch the SIM tray. Install your eSIM calmly before departure — you have 180 days to activate it after purchase — make the three settings above and leave your SIM card safely in the phone. Not equipped yet? Choose your Japan eSIM plan: QR code by email in 2 minutes. More questions? The FAQ has the answers.
