Ok, one of the tags on pixiv is 色っぽい長門. I'm thinking this is Amourous Nagato, but this doesn't look like any Nagato that I'm familliar with.... Any ideas anybody?

I think it's supposed to be Nagato Yuki from Haruhi, at least the uniform looks like theirs and her hair is silverish.

Yeah, it must be a more realistic rendition of her. I can't imagine it being anyone else.