We are traveling to Japan in March for a couple of weeks. Normally when visiting a country for a week or more I purchase a prepaid SIM card and insert it in my unlocked GSM phone (Sony Xperia Z Ultra).

Just read something peculiar: all the cell companies in Japan are CDMA, not GSM... is that true? Does this render my phone useless?
What options a person like me has? I am primarily interested in Data (Internet), not talk minutes.

Thank you