Akita Neru came out after the news bash about Miku users... It was flamed up over at 2ch, and someone created a mascot for all the flaming it occured. She is a "Fire-proof loid," basically a "firewall" sort of character that suppose to contain the flame... Her name, "akita neru" is a play on words meaing "飽きた" (i am full/bored), and "寝る" (sleep). Basically it's telling those people flaming, "no point arguing, go to sleep already."
-errorrrr

Akita Neru's origin was from a troll on 2ch crapped in Vocaloid-related threads. Anon commented that he wouldn't get angry only if the troll was a cute girl.
From that, Neru was created.
Nowadays, she mostly represents trolls who don't have enough patience to use Vocaloid software and complain about it.
-nfwu

Neru is technically a mix of Miku, Rin, and sometimes Len. And her voice might sound too much like Miku in this video, but she's showing more attitude than Miku tends to, so you can tell that there's some of Rin or Len. :/
And the whole point of Neru's singing voice is that she's too lazy to sing with her own voice, so she uses someone else's.
-HappyKittyGirl

shes suppose to sound like a higher pitched Miku since she is suppose to be a frustration of a user/troll who failed at using Miku's voice.
-KupoXP

HERE