Hatsune Miku
Hatsune Miku was the first Vocaloid developed by Crypton Future Media after they handled the release of the Yamaha vocal Meiko and Kaito. The name of "Hatsune Miku" was conceived soon after the Vocaloid 2 announcements, when an English and Japanese vocal were developed for the character. The intended design was delayed and later used for Megurine Luka instead. Miku was intended to be the first of a series of Vocaloids called the ""Character Vocal Series"", which included Kagamine Rin/Len and Megurine Luka. Each had a particular concept and vocal direction.
Hatsune Miku
It was mentioned that a 7th "Append" voicebank, a falsetto voice, had been recorded; however, since the developers didn't think it would be useful on its own, no plans were made for an independent release. During the Kagamine Append development, a "darkish Whisper/Sweet" append was being considered. Miku's English vocal was also due for a Vocaloid 2 release, but it was not released in the engine due to low quality.