"Upgrade options are valid on most published fare types ... except for the following: ... U.S. point of sale trans-Pacific fares beginning with H/K/V/Q and H/K/V/Q/M for flights between the U.S. and Hong Kong/China ..."

What I'm curious about though: I bought a K fare ticket IN JAPAN to go to CHINA and return. The restrictions wouldn't seem to apply, but I'm sure there's some catch。