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Leon and Lola were the first vocaloids ever to be released in 2004.

Proto-types of Kaito and Meiko were seen in 2003, and later, samples of Leon and Lola.

The very first Vocaloid, however, is a unknown proto-type only known by reference. It was the first vocal and was only capable of saying simple vowels with its first full word being "asa" (morning).

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Who is the first made Vocaloid
Who were the first Vocaloids