Koreans and Japanese are very shy. Talking to stranger is not a common thing in Korea. Most importantly, most koreans are not fluent in English, so they won't approach in first hand.
How you even get accepted to a university where the spoken language its only in Korea, how the school even accepts you if you don't know the language????
Grad school is mostly taught in english everywhere around the world (only if the major is related to let's say cultural heritage or treating of people (medicine, clinical psychology), it's in the native language). Also english Bachelor's programs exist
