you sure its about Touhou? Looks like Female Assassin from Fate/Zero to me

http://danbooru.donmai.us/posts?tags=female_assassin_%28fate%2Fzero%29

KojiroKouga said:

you sure its about Touhou? Looks like Female Assassin from Fate/Zero to me

http://danbooru.donmai.us/posts?tags=female_assassin_%28fate%2Fzero%29

Dunno. It's from a LOG with only Touhou tag.

The mask looks like her but the hair style and eye color are different.

Edit: It's tagged Fate on tumblr. Changed the copySource, still not confident about character.

I'm almost sure this is Hasson of Serenity, the assassin from Fate/Prototype: Fragments(http://typemoon.wikia.com/wiki/Assassin_%28Fate/Prototype:_Fragments%29)

As one of the pieces of art for serenity (http://i.imgur.com/jxnBxNH.jpg) has the same straps for that dress

zeparoh said:

The mask looks like her but the hair style and eye color are different.

That's because this is Child Assassin.

As Ultear suggest, her strap really convince me that she's assassin (fate/prototype_fragments) , the hair style is also more fit than Child Assassin's.