Hatsune Miku

Hatsune Miku, officially code-named CV01, is a Vocaloid software voicebank developed by Crypton Future Media and its official anthropomorphic mascot character, a 16-year-old girl with long, turquoise twintails. Miku's personification has been marketed as a virtual idol, and has performed at live virtual concerts onstage as an animated projection.
Miku uses Yamaha Corporation's Vocaloid 2, Vocaloid 3, and Vocaloid 4 singing synthesizing technologies, and Crypton Future Media's Piapro Studio, a standalone singing synthesizer editor. She was the second Vocaloid sold using the Vocaloid 2 engine and the first Japanese Vocaloid to use the Japanese version of the 2 engine. The voice is modeled from Japanese voice actress Saki Fujita.
The name of the character comes from merging the Japanese words for first, sound, and future, thus meaning "the first sound of the future", which, along with her code name, refers to her position as the first of Crypton's "Character Vocal Series", preceding Kagamine Rin/Len and Megurine Luka. The number 01 can be seen on her left shoulder in official artwork.

From Wikipedia (https://en.wikipedia.org/wiki/Hatsune_Miku) under Creative Commons Attribution CC-BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0/legalcode)