That's not anime /facestairs
http://en.wikipedia.org/wiki/VocaloidVocaloid (ボーカロイド, Bōkaroido?) is a singing synthesizer application
The four on the image are Luka Megurine, Rin Kagamine, Miku Hatsune and Len Kagamine, four of the what, 16 or something Vocaloids available. That's not counting Utauloids though.
There is no anime for this ( and never will be ) and the only sort-of-official manga is Hatsune Mix, but that's still rather questionable. The characters have no actual personality. It's all up to fan interpretation.
also, in during people not googling