What is the name of this Vocaloid? From Hatsune Miku Vocaloids.

Her name is Yowane Haku. She's not actually a Vocaloid she is a derivative character of Hatsune Miku that has been officially recognised.
for more information about her look here :)link

Haku

Actually, that's not a vocaloid, it's a fanloid. Haku and Neru are both fanloids, and teto is an UTAU. They're three of the most popular fanloids and UTAUs, so they put them in the game as a special part.

Haku is a girl, by the way! ♥︎ She's included in the Project Diva games, too, as you can see, but with the fanmade Vocaloids they don't include their voicebanks into the games.