Sakine Meiko is a japanese vocaloid that was initially released in November 2004, Her voice is provided by the Japanese female singer with the same name Meiko HaigÅ and after few years there is also Meiko for VOCALOID 3 version, I guess this is Sakine Meiko Cosplay from first VOCAOID.
In Sakine Meiko Cosplay this picture Chi Youn looks wearing a black dress with a gothic style touch, and if you see that pumpkins and skulls I think she was enjoying the Helloween night, well...actually i love her hood too, she looks cute with that.