This trio of friends remind me of (Now)Chibi-Miku, Chibi-Neru, and Chibi-Teto...
Come to think of it, Akita Neru and Yowane Haku are variants/clones of Hatsune Miku, while Kasane Teto and Yokune Ruko are from the UTAU family.
Heh,Teto and Chibi miku i understand as friend,but I didn't think Neru was one her friend too. I thought she only tried to get close with Chibi miku to get close with Len. Really? Neru i understand,but Isn't Yowane older then miku? She's like a gray and purple version of Meiko some how(both have big boobs and i think both of them drink). Must be her hair.