This is Taku Luka and she is basically a uneek ver. of Luka created in the same vain as Miku Hachune and other goofy vocaloid charicters much like that. Taku is the reason for Luka's obsession with Tuna and ended a long debate on Luka's character item.
If you want to read up on Tako Luka here is her vocaloid wiki page.
http://vocaloid.wikia.com/wiki/Tako_Luka
