I honestly don't think that there are extentions in her hair. It's a popular hairstyle with a lot of people I know from Hong Kong. They cut the top of their hair pretty short and leave the bottom section long and then they perm it.
So to get hair like that, I would cut my hair into pretty much two lengths then perm it if you want it permanently styled like that.
And another reason I dont think she has extentions is that in the picture it doesnt look like she has a lot of hair (extentions not only give length but usually volume as well) and I'm pretty sure that everything you see in the picture is all the hair that she has - this might sound confusing but what I meant is that all her hair is flipped to the front so that there isnt hair hiding on her back right now.
And the girl reminds me of a cute anime character!