I'm a native speaker of Korean and I'm currently learn Japanese (I'm intermediate). I suggest you to learn Korean first and then maybe you could move on to Japanese.
As we know, Korean only has one set of characters, it's called hangul. You just need to memorize and combine them. You can master it in only a week.
However, the Korean pronunciation sounds difficult for the people who aren't accustomed to it. But it might easier for you since you already mastered one of the Asian languages (I guess the pronunciation isn't simple like Japanese).
I'd say you better learn Korean first. It takes a great deal of practice to master a foreign language. You will probably can't master both languages only in one summer vacation, remember, it takes time. You can't master a foreign language in a short time; you have to study it step by step.
The-Magic-Of-Making-Up-Review
As we know, Korean only has one set of characters, it's called hangul. You just need to memorize and combine them. You can master it in only a week.
However, the Korean pronunciation sounds difficult for the people who aren't accustomed to it. But it might easier for you since you already mastered one of the Asian languages (I guess the pronunciation isn't simple like Japanese).
I'd say you better learn Korean first. It takes a great deal of practice to master a foreign language. You will probably can't master both languages only in one summer vacation, remember, it takes time. You can't master a foreign language in a short time; you have to study it step by step.
The-Magic-Of-Making-Up-Review