Originally Posted by
TheChallenge
I can say that the Marukai JCB Card works at places that only accept UnionPay in Hong Kong & Macau. I don't know if that holds true for Mainland China though.
That's interesting, as it probably has nothing to do with Discover then. They are careful to say Discover can be used at UnionPay merchants in
mainland China, though Hong Kong & Macau do not show up as countries at all, whereas Taiwan is listed as Diners Club only.
As for Discover-at-JCB in Japan, they say "
anywhere you see the Discover acceptance mark and at
almost all locations you see the JCB acceptance mark" (emphasis mine) though plenty of travelers have determined "almost all" to be a stretch.