I used Google image search with that picture and I'm pretty sure she is Korean. I also was before because she looks Korean and not Japanese at all to me.
About the signs in the background: I have to admit that I only can say that these are no Roman letters. But they can be Japanese, Korean or Chinese. And Chinese letters are used by the Japanese as well as by the Korean (also it is very seldom used there).
That's easy:
Goo Hara from
Kara. For her I even don't need any search.
Unfortunately it seems that Kara is breaking apart. First Nicole Yong-ju Jung left the group, then Kang Ji-young. But even Girl's Generation which was so constant in aspect of their members lost Jessica Jung. But better than Wonder Girls which disbanded more ore less - also the management denies it.