To derail this thread a little further - is that the sim available at the Softbank rental airport locations? I e-mailed them for Haneda's Simple Style device price list and they had the Blade Q android. Rather more than I need or want to spend. I think you mentioned sometime back that the Prepaid Sim had a fixed expiry date while sim in prepaid handsets could extend expiry date with recharge?

To bring it back and tie it into data connectivity - the iPhone needs a mobile/data connection to add money to Suica via app/Apple Pay but can be used in airplane mode going through ticket gates as long as there is enough stored credit. So repeat visitors could use the Wallet Suica stored value without a data connection (in case they want to pick up a sim in town vs airport)... Just like a regular IC card.