2007 Initial design
The design by Japanese CG artist aloha, is a female character similar to Hatsune Miku though her eyes are white and her hair is dark gray, her skin is metallic gray depending on her presented form, her fingernails are painted in red and floating above her arm is a spring onion. She wears a dark top with a key-shaped black heart outlined in red. The symbol parodies the heartless emblem from the video game series Kingdom Hearts. Under her skirt there appears to be red bloomers over black bike shorts, while her skirt is light gray with black trim and so are her thigh highs, followed by black slip on shoes. Her arm warmers, headphones, and futuristic ribbons are black and red. On her upper left arm is the infinity symbol.
2008 Later design
Zatsune's appearance gradually became very similar to the original Miku's and while it still holds the black and red theme, it changed from artist to artist which resulted in the current design having a puff sleeved top with a cleavage window and a split to show her navel. Her skirt is black and she's often is drawn with long boots or thigh highs when wearing heeled shoes. This designs continues to be the most popularized, meaning there is very few artworks that exist portraying Zatsune's initial design. She surprisingly does not have that much r-18 art with her more risque design.
The personality of Zatsune Miku has not been elaborated on particularly, but she is often depicted as dark or evil. As a fanmade character, she has no direct personality much like the original Vocaloids it is purely up to any fans.
She made her appearance in the upload "Hatsune Miku 3D, First appearance!!", which features Hatsune Miku in 3D mouthing one of her popular songs. In the PV Zatsune manifests and appears to be ready to fight Hatsune. However, Hatsune is prepared, along with her friends Hachune and Lulu. At the end of the PV, it appears Hatsune has been over taken by Zatsune's influence. Zatsune Miku, in Japan, used to be a parody character as an evil Miku or an anti-Miku attacker android. She was presented with a gray skin color and looked menacing. However, this concept is all but forgotten in Japan, whereas in the overseas community, her popular redesign is treated as a risque Miku, still evil, but in a rather different way. Any further official biographical information by the creator is unknown.
When the game Project Diva Extend was released, the Western fans mistook a Hatsune Miku module as Zatsune Miku. The performance of "Hold, Release; Rakshasa and Carcasses", portrays Hatsune as red-eyed, black-haired and pale. This design was simply carried from the original promotional video and bares no relation to Zatsune. Another common mistake with the Western fandom is viewing Zatsune as being influenced by Black Rock Shooter, this is debunked because BRS was introduced in December of 2007 and the song was released in June 2008. And prior to that fan artwork of the initial design can be viewed being before songs debut.
While Zatsune Miku has songs made to her name, she does not have any noticeable variation to the original, other than the fact that she sings risque songs. Some users use pitch manipulation to change her voice to be deeper.