The only CDMA carrier in Japan is au by KDDI, but they operate on a different frequency from Verizon Wireless. I don't really follow CDMA developments, but maybe the latest air interface chip is now compatible the handful of CDMA networks and frequencies worldwide.

If you got one of Verizon's global phones with UMTS 2100, then it can roam on NTT DoCoMo or Softbank's UMTS networks. Blackberry Tour is one such phone. There is no GSM coverage in Japan.