Pre-Paid SIM Limitations:
We can confirm that your ‘Japan Tourist’ SIM card will be active / ready for use upon arrival and your 8, 16 or 31 day service duration will just begin from the day that your SIM card first connects to the Docomo (IIJ) network within Japan.
The SIM card will also automatically cease working when your 8,16 or 31 day service duration has ended.
Please note that it will not possible to extend the service duration / the SIM card can only be used once and so you would be required to purchase additional SIM cards if service is required for a longer duration.