http://www.itochu.co.jp/en/news/2014/1406041.html
I didn't know that
DCC was in use in Japan but it has apparently been around since 2009, and there is now a deal in place between Travelex, UC and Itochu to expand its reach in preparation for the Olympics.
Be careful when using a foreign CC in Japan, particularly at tourist-oriented places, as you might get hosed on the exchange rate...