[Kikaru]

^I dunno, I speak fluent Mandarin and I don't think Korean sounds anything like the mix at all.

But the two languages have similar backgrounds and everything, kind of like French and Spanish. But yes, environment plays a factor, especially in a less-diverse environment, you tend to learn the language more easily. Plus BoA was pretty young when she started to learn Japanese, and Children learn languages easier. Personal experience for me.