For SIM cards:
Please refer to Docomo’s official site for the service coverage area:
Docomo Service Area (Website in Japanese Only)
For Pocket WiFi:
・For 5 GB or 30 GB plan:
Docomo Service Area (Website in Japanese Only)
・For 100 GB plan:
Softbank Service Area (Website in Japanese Only)
・For UQ WiMAX (Unlimited plan):
UQ WiMAX Service Area (Website in Japanese Only)
If you have trouble looking up the service area in Japanese, please feel free to contact us here.