Firsty

Firsty offers an unusual freemium model, with an ad-supported tier that costs nothing. If you'd rather pay, prepaid data starts at €0.98 per GB and never expires, giving you flexibility to use it on your own schedule.

Firsty works well for budget travelers or those who value data that doesn't vanish after 30 days. The automatic connection to Docomo, KDDI, and SoftBank means setup is simple, and you're ready to use the network without fiddling.