Adachi Rei

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Adachi Rei VOCALOID5 VOCALOID6 | UTAU REPLIVOICE & others | Songs Albums Notable Originals

Adachi Rei (足立レイ) is an upcoming Japanese VOCALOID and vocal synthesizer character created by missile39, originally released for the UTAU vocal synthesizer program in October 2019. In October 2021, she received a Japanese text-to-speech library developed in collaboration with AI, Inc.'s A.I.VOICE software under the name REPLIVOICE Adachi Rei. She has also received numerous fan-made conversions of her original CV UTAU voicebank such as a VCV voicebank developed by Near,^[1], a DeepVocal port developed by ematares^[2], and a DiffSinger port by tigermeat, in addition to numerous other ports and conversions, all of which have been released with permission granted from missile39.

Through an official collaboration with missile39 and Yamaha Corporation's VOCALOID FAN-ding initiative following a successful crowdfunding campaign hosted by the Japanese platform CAMPFIRE, Adachi Rei is expected to release for both the VOCALOID5 editor, as a standard concatenative voicebank, currently showcased as a prototype, as well as an AI voicebank expected to be released for VOCALOID6.^[3]

Her voice was generated in Audacity specifically to create a choppy and robotic sound.

Concept[]

Adachi Rei is conceptualized to be a life-size character humanoid bishoujo robot. Rei began as a fully computer-generated UTAU. The process was done by adding sine waves together in the Audacity audio software (also known as additive synthesis), creating consonants from a synthesized xylophone sample, running the samples through the VST plug-in Vocalizer, and finally editing it all once again in Audacity.^[4] She has a choppy and robotic sound.

Etymology[]

Her code name "HCI3-P0", stands for Humanoid Character Interface 3 Prototype. The "A" in Adachi (足) may mean 'foot', 'sufficient' or 'satisfy' while "Dachi" (立) means 'stand' or 'exist'. While a meaning can be derived from the name, such as "to stand on one's feet" or "to satisfy existence", Adachi is simply a common Japanese surname. "Rei" (レイ) is a common Japanese given name. It is also one of the pronunciations of 0 in Japanese, which could reference "Prototype 0"

Appearance[]

Adachi Rei has orange, shoulder length hair styled into a side-ponytail on the left side of her head. Her headgear consists of a black, router-like device with antennas, a white ribbon, and a microchip hair clip. Her headset is black with power switches, various computer ports, and a headlamp. She has orange eyes with a camera lens in the pupil of each eye. Her outfit consists of a black turtleneck, baggy white jacket with "00 ADACHI REI" on the left side with black pockets, loose AUX/USB wires in red and black, plaid-patterned grey pleated culottes (often depicted as simple grey shorts), orange belt, black leggings, and a pair of orange and white sneakers. According to missile39, her clothes are based on a firefighter's uniform: the orange stripes resemble reflective safety stripes on a turnout coat, to make arm and leg movement easily visible.^[5]

Relations[]

Chahakobi Meguri - Prototype.

History[]

Pre-VOCALOID[]

In 2017, production was started on creating Adachi Rei. After successfully building a life sized Hatsune Miku robot, missile39 went on to create their own original character robot. On February 15, 2017, a CAMPFIRE crowdfunding campaign was launched to help fund the construction of the robot. The goal was set for 3 million yen and surpassed that goal hitting a total of ¥3,596,499 from 184 backers. The rewards for backing are set to be sent out in December 2021.^[6] To go with the robot, a singing voicebank was to be created for UTAU. Rei's voice would be modified from various digital synthesized samples to create a voicebank capable of singing in Japanese. The samples were modified in Audacity to create a more genuine robotic, choppy, and low-quality artificial sound.^[7] The parts for her robot were digitally modeled and 3D printed. Her UTAU voicebank was finally completed and released on October 12, 2019.

On March 9, 2021, a new CAMPFIRE campaign went up; this time for a REPLIVOICE software powered by A.I.VOICE. Unlike the previous UTAU voicebank which is capable of singing, this voicebank would be capable of speech. The goal this time was set to 3.5 million yen and once again surpassed it at ¥4,547,039 form 256 backers.^[8] On July 30, 2021, Mechanical Girl released a press release revealing the final boxart and release date for Rei. She was set to be released on October 23, 2021.^[9] A trial version was also released on her BOOTH product page alongside the ability to buy her voicebank both physically and digitally.^[10]

On May 3, 2025, tigermeat posted that he had a surprise in regards to Adachi Rei to show soon.^[11] This was revealed to be a port of Rei for DiffSinger, which was mainly a Japanese voice library. But through Cross-Language Synthesis, she was able to sing in English, Mandarin Chinese, Korean, French (noted to be trained with "Millefeuille"), Spanish, Thai, Brazilian Portuguese, Russian, German, Italian, and Polish, with more planned in the future.^[12] She was released on the same day with permission from missle39, and the library would be managed and updated by tigermeat.^[13] According to her page on tigermeat's website, the audio used to create her DiffSinger library was sourced from her UTAU 3.1.2 voicebank. On May 7, tigermeat had thrown together more data for Rei to assist with her range issues. Another round of training was planned within the next few weeks after labelling.^[14] He noted that he had Rei "record" a CVVC reclist, and after labelling, he manually shifted the pitch a little. Using extra samples, he added consonants to create non-Japanese sounds, such as "fr/en", "fr/un", and "en/ax".^[15] This set her to fifteen minutes of data as opposed to her initial eight minutes in the version he had released. This would help her sound more stable in languages other than Japanese.^[16]

On September 1, tigermeat accidentally deleted all of the DiffSinger voicebanks under his management while attempting to clean his Google Drive account. While reuploading them, he decided to upload a slightly upgraded version of Rei's DiffSinger voicebank rather than wait for a larger collective update.^[17]

VOCALOID[]

On November 25, 2025, Yamaha launched the VOCALOID FAN-ding initiative, a collaboration with Japanese crowdfunding platform CAMPFIRE where Yamaha plays a support role in crowdfunding projects for future VOCALOID voicebanks.^[18] The first project to be announced under the program was a campaign to bring missile39's UTAU voicebank Adachi Rei to the VOCALOID software; in the intro video, a test VOCALOID5 voicebank built from samples of the purely-artificial voice was showcased singing a very short snippet of "Pond Rain" (池の雨), a cover of a German folk song.^[19] The crowdfund campaign was scheduled to open on December 1 and run for a total of 61 days;^[20]^[21] among its stretch goals was an attempt to derive an AI voicebank for VOCALOID6 to allow her to sing not just in Japanese but also in English and Mandarin Chinese.^[22]^[23] Less than 24 hours after the crowdfund started on December 1 (as expected), both the main goal (the concatenative VOCALOID voicebank) and the second stretch goal (the VOCALOID:AI voicebank attempt) were met.^[24]

Two other prospective vocals were also announced to be applying to VOCALOID FAN-ding: Akatsuki Luci, an AI voicebank based on the voice of the homonymous virtual YouTuber,^[25]^[26] and a singing AI voicebank for Tsunose Kotone, a web-radio personality who originally debuted as a text-to-speech voicebank for the A.I.VOICE software in May 2023.^[27]^[28] No start dates were revealed for these two as they were still making preparations.

Marketing[]

WIP

Voicebanks[]

Adachi Rei - Song: Singing voicebanks released for Adachi Rei. Notable fan-conversions listed.

Adachi Rei (UTAU), October 12, 2019
Adachi Rei VCV (UTAU), April 4, 2020
Adachi Rei (DeepVocal), October 29, 2021
Adachi Rei DS (DiffSinger), May 3, 2025
Adachi Rei (VOCALOID5), successfully crowdfunded as of December 1, 2025
Adachi Rei (VOCALOID6), successfully crowdfunded as of December 1, 2025

REPLIVOICE Adachi Rei: The talk voicebank of Rei

REPLIVOICE Adachi Rei (REPLIVOICE), October 23, 2021 (Windows)
REPLIVOICE Adachi Rei (REPLIVOICE), May 21, 2024 (macOS)^[29]

Music featuring Adachi Rei[]

On this wiki, Adachi Rei is featured in 0 songs, 0 albums, 0 series, and 0 events.

There are listings for notable and original songs.

Search for music featuring Adachi Rei [show/hide]

"VOCALOID Adachi Rei" on Niconico Video
"VOCALOID Adachi Rei" on YouTube
"VOCALOID Adachi Rei" on bilibili
"VOCALOID Adachi Rei" on SoundCloud
"VOCALOID 足立レイ" on Niconico Video
"VOCALOID 足立レイ" on YouTube
"VOCALOID 足立レイ" on bilibili
"VOCALOID 足立レイ" on SoundCloud

Reputation[]

Status

Google Trends

Rei Adachi Rei

Achievements

First vocalist by missile39
First original A.I.VOICE vocal to apply for crowdfunding for a VOCALOID voicebank
First fully artificially generated VOCALOID voicebank
First VOCALOID without a human voice provider

References[]

External links[]

Language	Description	Site
Japanese	Mechanical Girl official website for Adachi Rei	Link
Japanese	足立レイ, the official Twitter account for Adachi Rei	Link
English	deviantArt, art and media community	Link
Japanese	Pixiv, art and media community	Link
English	VocaDB, artist database entry	Link

Navigation[]

Template:Missile39 navbox

[1] ttps://youtu.be/i_GNVSWulGQ

[2] ttps://soundcloud.com/mars-392276485/10-deepvocal-release-motivation-is-dead

[3] ttps://camp-fire.jp/highlights/vocaloid-fan-ding#top

[4] ttps://www.youtube.com/watch?v=3Ev_lJeAgYM

[5] ttps://youtu.be/ZC28u1Dqcpg?si=7gyunBjRFEoY6jV4&t=1466

[6] Robot CAMPFIRE

[7] ttps://www.youtube.com/watch?v=3Ev_lJeAgYM

[8] REPLIVOICE CAMPFIRE

[9] ttps://mechanicalgirl.jp/合成音声ソフト/

[10] BOOTH product page

[11] ttps://bsky.app/profile/tigermeat.xyz/post/3lobunjfrv22t

[12] ttps://bsky.app/profile/tigermeat.xyz/post/3lock72pvoc2g

[13] ttps://bsky.app/profile/tigermeat.xyz/post/3loc53esw222t

[14] ttps://bsky.app/profile/tigermeat.xyz/post/3lomiuctfbs2i

[15] ttps://bsky.app/profile/tigermeat.xyz/post/3lomivirnq22i

[16] ttps://bsky.app/profile/tigermeat.xyz/post/3lomm5jrvzk2i

[17] ttps://bsky.app/profile/tigermeat.xyz/post/3lxvc425cuc2q

[fanding-18] ttps://camp-fire.jp/highlights/vocaloid-fan-ding

[19] ttps://www.youtube.com/watch?v=f7cKqn-htiQ

[20] ttps://x.com/MechanicalGirl0/status/1993187881553477992

[21] ttps://x.com/missile_39/status/1993192295446069430

[22] ttps://mechanicalgirl.fanbox.cc/posts/10956073

[23] ttps://camp-fire.jp/projects/897570/view

[24] ttps://x.com/TakoyakiDonuts/status/1995704552306475149

[25] ttps://x.com/AkatsukiLuci/status/1993169657315180606

[26] ttps://x.com/AkatsukiLuci/status/1993170216726266071

[27] ttps://x.com/TsunoseKotone/status/1993167917719208092

[28] ttps://x.com/TsunoseKotone/status/1993168163060826232

[29] ttps://x.com/MechanicalGirl0/status/1792573554736922652

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