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Otori Kohaku AKAZA VOCALOID4 | A.I.VOICE | Songs Albums Notable Originals

This article is about the VOCALOID4 software known as a voicebank, dubbed unity-chan!. If you are looking for the VOCALOID character then click here.


Otori Kohaku (Unity-chan) was an existing 3D model and character before her VOCALOID announcement, with her original debut in December 2013. She was created as a mascot for Unity, a cross-platform game engine developed by Unity Technologies, for the Japanese division. She grew popular with gamers and interactive application writers, as assets for her character were available as a free download. This led to her appearing in a variety of developers' projects.

She appeared as a guest in Vocalo-P ni Naritai, the magazine that released Rana's VOCALOID3 voicebank trials and tutorials.[1]

In the summer of 2015, her provider, Asuka Kakumoto, was scheduled for recording. There were 3 recording sessions over the course of four days with one day set aside for testing. In total, Kakumoto spent three of those days recording. This was the company's first experience with VOCALOID, and while Kakumoto had grown used to acting as the character, she had never done so extensively, nor had she ever had to do a singing role for Kohaku or perform a singing role as a voice actress. After the testing period, production went smoothly.

Some parts of the vocal were unfamiliar to Kakumoto, but she continued without allowing herself to worry about this. She had to do homework for the process and even faced issues such as her throat drying up. She felt that the process of creating a VOCALOID lead to the rediscovery of her character. Over the course of the three days, she improved at producing results, and because of this, the quality improved. She also found it a strange experience when she had to duet with the VOCALOID voice, which was referred to as "AKAZA" because she would sing as Otori Kohaku herself (due to this, AKAZA has become an alternative design for Kohaku). She had to put some effort into distinguishing herself from the VOCALOID voice. The production staff involved with the duet song felt as if they had two vocalists, and at one point, Kakumoto was so struck by the duet with her own VOCALOID that she felt that the VOCALOID vocal couldn't be her own voice.

As she was recorded for VOCALOID4 and not VOCALOID3, one of the developers, known as "Baba," reported in an interview that the vocal had a different sense of direction. VOCALOID4's style differs from VOCALOID3's greatly, so vocals were focused on bringing out the vocalist's vocal characteristics and traits, while the methods used for VOCALOID3 were reported to be easier to fit for music. This meant the developers had to learn more about the character "Unity-Chan" and how to bring out the best in the vocalist's traits.[2]

On August 26, 2015, Kohaku was officially announced to be released for a software separate from VOCALOID4 known as "Unity with VOCALOID". She was expected to release around December and would be compatible with both VOCALOID for Unity and the VOCALOID4 engine.[3][4]

On December 4, it was revealed that Kohaku would be sold as a boxed copy on December 29 at Comiket 89, at booth no. 131. A special pre-release package known as the "Special C89 (VOCALOID4 Library unity-chan!) PROJECT:AKAZA Special Package" (『C89特別仕様 『VOCALOID4 Library unity-chan!』PROJECT:AKAZA スペシャルパッケージ』) was sold for ¥10,000. This was not included in the regular product.

The digital download and mobile version became available in January.[5] Kohaku and AKAZA were officially released on January 14, 2016.

Product Information[]



UNITE IN THE SKY! / Google Cardboard VR YouTube
UNITE IN THE SKY! / Samsung Gear VR YouTube
UNITE IN THE SKY! / Oculus Rift DK2 VR YouTube


Product Information
  Optimum Range: G2 ~ G4  Optimum Tempo: 80 ~ 220 BPM
  Total Tempo (min-max): 140 BPM  No. of Keys: W ~ 15, B ~ 10, Total ~ 25
  Trial/Demo Vers?: No  Starter Available?: No  App vers.?: Yes
Package details as noted:

The vocal is designed to be a vivid, high-quality voice.[6] As a result of the recording style of VOCALOID4 vocals, the recordings focused on vocal traits, so the vocal sounds very much like the character "Unity-Chan." The voicebank represents both characters featured on the boxart and has one voicebank for both characters.

Due to previous developments, one can access 300 extra .wav files of Kohaku/AKAZA saying various things, which can be downloaded from the character "Unity-Chan's" own website.[7] These recordings are included with the Unity with VOCALOID version.

Vocal traits as noted:
  • Their tempo range allows them to be used for a wide range of songs. Because their voicebank is optimal for fast tempos, they're not very good for slower songs.
  • Their voice is energetic and lively in tone.
  • Compared to the Unity with VOCALOID version, the VOCALOID4 quality is higher and has access to GWL.

Voicebank sample

unity-chan! for Unity with VOCALOID