Kasane Teto (重音テト) is a Japanese (and later English) UTAU who was originally created as a troll "VOCALOID" by fans. Her surname 重音 (Kasane) literally means "heavy sound" or "overlapped sound;" while these interpretations are widely accepted among fans, TWINDRILL has not released any announcements about the meaning of the name.[3] Her name テト (Teto) comes from Tetopettenson, a parody song of Le Beau Tambour.
Although her original voicebank was only for use in UTAU, many people still mistook her for a VOCALOID (and still mistake her for one to this day). Though she had no final voicebank released for the VOCALOID engine, there were attempts in 2012 to release Teto for VOCALOID in collaboration with AH-Software Co. Ltd., and she later had a private beta voicebank with Crypton Future Media, Inc. in 2017. She later released as a speech voicebank for the TALQu text-to-speech synthesizer in January 2022,[4] an AI singing voice database developed by AH-Software for Synthesizer V Studio in April 2023,[5] and an AI text-to-speech voice library also by AH-Software for VOICEPEAK in April 2025.[6]
Her voice provider is Mayo Oyamano.
History
Following the rising popularity of Hatsune Miku, "Vippers" (Vip News Bulletin@2ch users) schemed a troll "new VOCALOID release" as an April Fool's joke. Sen (線) provided the rough sketch and Nobuyo Oyama, a spoof for Doraemon's former voice actress Nobuyo Oyama, provided the vocal. The Teto project continued after the troll campaign, and her vocal was recorded again for the use on UTAU, which vocal synthesis software was released two months earlier. UTAU and Teto were both unnoticed among VOCALOID composers at first, but during the last half of the year of her release several creators started composing songs for Teto, causing her fame to be established during the following year. The voice provider's name reading was then changed to Mayo Oyamano (小山乃 舞世 Oyamano Mayo) to avoid unnecessary confusion.
Teto was given official acceptance to piapro on April 1, 2010, and to Project DIVA on October 10, 2011.
In 2012, Tomohide Ogata from AH-Software Co. Ltd. came into contact with Mayo Oyamano, discussing the idea of turning Teto into a VOCALOID. However, the voice could not be reproduced in a satisfactory manner.[7][8]
In February 2017, Wataru Sasaki (also known as simply "wat"), from Crypton Future Media, Inc., tweeted that Teto was tested as a beta in the VOCALOID engine. At the time, wat was researching the differences in how VOCALOID and UTAU connected phonemes, with UTAU having very distinctive characteristics.[9] He had obtained permission from Teto's creators and attempted to insert fifteen UTAU phonemes into VOCALOID, but the individuality of the voicebank was not present, which disappointed him.[10] Unless GMM or morphing was used to directly inherit the UTAU engine's quirks in a well-balanced way, the characteristic points unique to the original voice synthesizer could not be preserved. He noted that the result did not come close to the individuality that made UTAU what it was. He would be continuing the research until early April.[11] On March 8, wat tweeted about his research again, where the task of "considering the charm of UTAU and the differences in voices" led to inspiration, allowing him to calmly and assess the strengths and weaknesses of VOCALOID, hoping to use this research in future updates for Hatsune Miku and others.[12] On March 17, wat tweeted that he had intentions of sending Teto's sample to TWINDRILL.[13] On April 1, he reported that he was drawing each overtone of Teto one by one.[14] On April 28, after consulting with TWINDRILL, Rena Maeda's participation was offered because he was a fan of her singing voice.[15] The next day, wat tweeted that before he went to Makuhari, he needed to finalize the planning arrangements with Nippon Columbia Co., Ltd. or else the next project for Teto would not come to fruition.[16] wat contacted TWINDRILL and other related individuals on April 30.[17]
On July 13, wat tweeted that a collaborative album featuring Hatsune Miku, Kasane Teto, and Maeda Rena was in production.[18][19] Teto was planned to sing around two or three songs, and according to wat, it was a "race against time".[20] However, on July 15, wat noted that during the album's information release, some media outlets referred to Teto as a VOCALOID. Information had been shared internally to be more cautious about the topic in the future and he apologized for the oversight.[21] On July 14, he tweeted that the rough draft data for Teto's singing was completed and sent to TWINDRILL. The robotic voice had more emotion than expected.[22]
Other voice library productions
Teto was announced to have a TALQu speech voicebank in July 2021, which later released on January 8, 2022.[4] She was also released as an AI voice database for Synthesizer V Studio on April 27, 2023,[5] and then as a voice database for VOICEPEAK on April 24, 2025.[23]
Impact on VOCALOID
The first cover song using Teto was created as early as April 6, 2008,[24] and her signature song "耳のあるロボットの唄 (Mimi no Aru Robot no Uta)" was published on June 10 by Mimirobo-P. Since then several creators including Lamaze-P, Telmin and Death Ohagi started to create Teto songs. Some of these early works include "Fake Diva", "Triple Baka", "Kasane Territory", and "Popipo Mk-II".
This trend changed on August 1, 2009, when UTAU was updated and VCV voicebanks became available. Teto's VCV voicebank was released on October 20, 2009 and her singing became more natural than before. This evolution made more DAW users turn their eyes towards Teto. Many Teto songs were posted to Niconico, and Teto and UTAU established a place among VOCALOID.
Marketing
Since her adoption for Project DIVA in 2011, Teto has had various unusual chances for a non-VOCALOID vocal synthesizer character to appear in media.
Media Appearances
Japanese record label Avex released a CD album containing Teto songs on October 10, 2012.
From April of 2013 to March of 2014 Teto was adopted as an official character for Hokkaido Broadcasting Co., Ltd.
The Kabuki play Kuruwa Kotoba Awase Kagami, where Teto acted as a side character, was performed on April 29, 2017. The story was inspired from "Yoshiwara Lament", one of the most famous songs of Teto.
In the CD album 手塚治虫と冨田勲の音楽を生演奏で, released on September 6, 2017, Teto collaborated with Miku.
In honor of her 10th anniversary, Teto made an appearance in Hatsune Miku Symphony 2018-2019 and performed 3 of her popular songs.
Figurines
An official Nendoroid has been made for Teto.
An official figure based on her popular song "Yoshiwara Lament" was made for Teto.
Literature
In Maker Hikoushiki Hatsune Mix, Teto makes a cameo appearance in chapter 14, Kagamine Mix.
Video Games
Teto, along with other non-VOCALOID characters, is a playable character in the Project DIVA series.
Product Information
| Product Information | |
|---|---|
| Optimum | |
| Genre: Pop, Anison Optimum Range: A#3~E#5 Optimum Tempo: 70~150 BPM | |
| Package details as noted: | |
|
Teto is held under license by Team TWINDRILL and usage of her image and voicebank must comply with their licensing agreement. Her initial release is BOUCALOID on April 1, 2008 with triphones on September 17, 2011, and her second release is BOUCALOID APPEND on October 1, 2012. | |
| Vocal traits as noted: | |
|
As noted:
| |
| Software issues as noted: | |
| |
Additional information
Reputation
Status
| Sales |
|
She can be downloaded for free from her website. She is also regarded as one of the most used UTAU in Japan, if not the most used. |
| Reaction |
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Since her first voicebank release, Kasane Teto have received a very positive response from the public. Kasane Teto has more than 20.000 videos starring her at Niconico. |
| Impact |
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| Misc |
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She has made guest appearances in official VOCALOID media by Crypton Future Media such as Project Diva. In fact, because of her fame and constant guest appearances alongside VOCALOIDs, she has been often been mistaken as a VOCALOID. |
| Achievements |
|
References
- ↑ Q&A via Wayback Machine: 性別がキメラってどういうこと？
What does "gender: chimera" mean? - ↑ Q&A via Wayback Machine: テトは本当に31歳なの？人間に直すと年齢は半分になるの？
Is Teto really 31 years old? Should her human age be counted by half? - ↑ Q&A via Wayback Machine: 重音テト制作時に参加者の一人から提案されて採用された苗字ですが、その由来は不明です。
(This is) a surname suggested by a vipper (denizen of vip@2ch) and we adopted it, but where this name was from is not clear. - ↑ 4.0 4.1 https://x.com/twindrill_teto/status/1416739783213142018
- ↑ 5.0 5.1 https://www.ah-soft.com/press/synth-v/20230403.html
- ↑ https://www.youtube.com/watch?v=V1WDbqfA9IQ
- ↑ https://www.youtube.com/watch?v=k-tMiZmwLvY
- ↑ "Synthesizer V AI Kasane Teto Announced by AHS and Twindrill" - a summary and translation of KASANE TETO's debut contents by MARUMAIN
- ↑ https://x.com/vocaloid_cv_cfm/status/835103770488909826
- ↑ https://x.com/vocaloid_cv_cfm/status/835104350175318017
- ↑ https://x.com/vocaloid_cv_cfm/status/835105242928705536
- ↑ https://x.com/vocaloid_cv_cfm/status/839569093803962368
- ↑ https://x.com/vocaloid_cv_cfm/status/842664847682629632
- ↑ https://x.com/vocaloid_cv_cfm/status/848201151136776192
- ↑ https://x.com/vocaloid_cv_cfm/status/857915623703166976
- ↑ https://x.com/vocaloid_cv_cfm/status/858236162208546816
- ↑ https://x.com/vocaloid_cv_cfm/status/858615425264898048
- ↑ https://x.com/vocaloid_cv_cfm/status/885655395582132225
- ↑ https://x.com/vocaloid_cv_cfm/status/885662994054602752
- ↑ https://x.com/vocaloid_cv_cfm/status/885677061465022464
- ↑ https://x.com/vocaloid_cv_cfm/status/886162936309231616
- ↑ https://x.com/vocaloid_cv_cfm/status/885830186775715841
- ↑ https://www.ah-soft.com/voice/teto/
- ↑ https://www.nicovideo.jp/watch/sm2910040
External links
| Language | Description | Site |
|---|---|---|
| Japanese | Kasane Teto Official website | Link |
| Japanese | Kasane Teto Blog Official blog | Link |
| Japanese | atWiki Kasane Teto Wiki | Link |
| Japanese | @twindrill_teto The official Twitter account for Kasane Teto | Link |
| Japanese | TwinDrillTeto Official YouTube channel | Link |
| English | UTAU Wiki Kasane Teto page | Link |
| English | UTAU Wiki 2.0 Kasane Teto page | Link |
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