The South Korean experience was far less extensive. During my travels there on business, I actually found my second language (Japanese) was more likely to be understood than my first (English).
When I was in Seoul in the ‘80s on business the English there was very good, as it was taught from grade school. And the population was very pro-American. The Japanese interrelationship was arguably closer longer term, but with much more resentment against the Japanese than the Americans, who were allies and more recently a major presence—militarily and in civil society, etc.