The chibi blank faced version of Vocaloid Hatsune Miku. She is drawn in the big faced, white eyed style made famous by doujin circle Harukaze Kouho.
Hachune Miku first appeared in NicoNico through the Ievan Polka song, spinning a stalk of negi reminiscent of Orihime (Bleach), which spread to a meme called leekspin.
This video permanently tied negi to Hatsune Miku.
This tag implicates hatsune_miku (learn more).