After doing a little research it seems that people who are not residents of japan cannot legally get a voice\data SIM card. They can however get a throw away prepaid phone that does voice AND a data-only SIM card for their separate smart phone that needs to be activated in-country.
Anyone know a Japanese Prepaid Data SIM card that will work with the sprint variety of the HTC one? I've tried b-mobile prepaid Data-only sim (DoCoMo) to no avail. HTC One is not in their online list of "approved" devises, but i figured id give it a shot anyway because it met the LTE 800 spec.
Here is a link to their site if you want to take a look around:
Supported Devices | b-mobile VISITOR SIM