Vocal Synthesizer Wiki

Kaai Yuki (()(あい)ユキ) is a Japanese VOCALOID developed and distributed by AH-Software Co. Ltd., and was initially released in December 2009 for the VOCALOID2 engine. Yuki's vocals are based on an elementary school student. Since the voice provider was a young fourth grade girl at the time, her identity was never revealed for legal reasons. Her voice provider was able to speak about Yuki for the character's 10th anniversary, but she still remains anonymous.[1] She was the first female VOCALOID whose voice samples were not produced from an adult.

She was updated to the VOCALOID4 engine in October 2015 and used a new voice provider for the growl components. This was due to her initial provider maturing, making re-sampling problematic.[2]


She and Hiyama Kiyoteru were released as "student" and "teacher" VOCALOIDs.


The characters of her surname, "Kaai" (歌愛), mean "song" and "love" respectively. Her given name, "Yuki" (ユキ), comes from the kanji form (雪), meaning "snow". Together, her name means "love song of snow".


Yuki is meant to be portrayed as a 9-year-old elementary school student. She is said to be "as tall as 10 big apples" and "as heavy as 86 apples". Her red randoseru is a motif of YAMAHA's wind controller, WX5. Originally she was blonde in concept art.




Yuki, along with SF-A2 miki and Hiyama Kiyoteru, were introduced to expand the VOCALOID market and give producers more vocal options to utilize.[3]

Until May 2011, all AH-Software VOCALOIDs were banned from KARENT.


Kaai Yuki - Natural
The Yuki vocal was designed to give a child-like vocal to producers. She represents a child's voice and was voiced by an actual child, making her a realistic representation of a child. The vocal is that of an amateur singer and does not give professional singing quality. However, due to the vocal source being of a child, the "natural" vocal has encountered updating issues over time.



The first three AH-Software VOCALOIDs were slow to gain popularity and were amongst the least popular VOCALOIDs for a while. In 2010, Yuki was the second most popular of the trio.[4]


An independent search on niconico revealed that most VOCALOIDs, Yuki included, had less than 1,000 videos uploaded in 2011 between July 1 and December 15.[5]


  • One of the first 3 AH-Software VOCALOIDs
  • One of the two first female AH-Software VOCALOIDs
  • First vocal to be provided by a child
  • First female vocal to be provided by a child


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