Tell the employer exactly what the job entitles:
I was working with a Korean native teacher(s), teaching students between the ages of X and Y to learn English. My role in the classroom was to facilitate production of language, to encourage and nurture ability, and to promote learning. While teaching, I learned to do a, b and c. I found working with someone else to be (helpful/hindering/stressful/fun).
I took the job in South Korea to put myself in a different situation, a different lifestyle, and a place where I didn't understand the language, to see how I'd be able to cope and work in an unknown environment. I believe I did rather well as I was able to work successfully there for X number of years. While in South Korea, I picked up a bit of the language also, which may prove to be useful in the future, should I come across any Korean people while working in my home country. I'll be aware of their customs, their culture and be able to communicate a little with them.
This is what I'd be telling an employer, or something to this effect. As I hope some day to return to teaching in my own country as well, I'd be contemplating learning Korean as fluently as I can so that I can teach Korean as well as Japanese.