Kasane Teto (, ) is a virtual singer software (voicebank) created on the Japanese

textboard A textboard is a simple kind of Internet forum; most textboards require neither registration nor entry of a screen name. Textboards, like imageboards, were invented in Japan, but they remain relatively unknown outside it, in contrast to imagebo ...

2channel , also known as 2ch, Channel 2, and sometimes retrospectively as 2ch.net, was an anonymous Japanese textboard founded in 1999 by Hiroyuki Nishimura. Described in 2007 as "Japan's most popular online community", the site had a level of influe ...

for

April Fools' Day April Fools' Day or April Fool's Day (rarely called All Fools' Day) is an annual custom on the 1st of April consisting of practical jokes, hoaxes, and pranks. Jokesters often expose their actions by shouting "April Fool " at the recipient. ...

2008. Although the software was initially created as a

hoax A hoax (plural: hoaxes) is a widely publicised falsehood created to deceive its audience with false and often astonishing information, with the either malicious or humorous intent of causing shock and interest in as many people as possible. S ...

and did not exist, it later was actually produced and made compatible with singing voice synthesis software

UTAU UTAU is a Japanese singing synthesizer application created by Ameya/Ayame (). This program is similar to the VOCALOID software, with the difference being it is shareware instead of under a third party licensing. Overview In March 2008, Ameya/A ...

, allowing it to sing. Teto has been introduced as a "diva born from a

". Kasane Teto was also released as a voice model in 2021 for TALQu, a deep learning-based free speech software, in 2023 for , a commercial singing voice synthesis software, and in 2025 for , a text-to-speech software.

Character

Kasane Teto is officially stated to be 15 years old. However, her developers note that fans have differing interpretations of her actual age and are free to interpret it differently if they prefer to, mentioning that some fans believe Teto ages differently from humans due to her being a chimera and is therefore a teenager when her age is converted to human years, while other fans do consider her official age of 31 to be her actual age in human years. In her earliest design, she was 159.5 centimetres tall and weighed 47 kilograms. She is listed as liking

baguettes A baguette (; ) is a long, thin type of bread of French origin that is commonly made from basic lean dough (the dough, not the shape, is defined by French law). It is distinguishable by its length and crisp crust. A baguette has a diameter ...

(which she is frequently depicted with in

fanart Fan art or fanart is artwork created by fans of a work of fiction or celebrity depicting events, character, or other aspect of the work. As fan labor, fan art refers to artworks that are not created, commissioned, nor endorsed by the creator ...

) and being a

tsundere is a Culture of Japan, Japanese term for a character development process that depicts a character with an initially harsh personality who gradually reveals a warmer, friendlier side over time. The word is derived from the terms (adverb, 'mo ...

. Kasane Teto is portrayed as a youthful girl with reddish hair styled in spiraling

twintails A woman with long pigtails and braids. In the context of hairstyles, the usage of the term pigtail (or twin tail or twintail) shows considerable variation. The term may refer to a single braid, but is more frequently used in the plural ("pi ...

resembling

drill bits A drill bit is a cutting tool used in a drill to remove material to create holes, almost always of circular cross-section. Drill bits come in many sizes and shapes and can create different kinds of holes in many different materials. In orde ...

, a style her developers refer to as "twindrills.". She typically wears a uniform-style outfit with a red and black color scheme, which has become a recognizable part of her image. Her personality is generally portrayed as mischievous.

History

Creation

Kasane Teto's origins come from

, a Japanese bulletin board. In 2008, a group of users devised a plan to make a fake Vocaloid character. Character names, hairstyles, genders, ages, likes, dislikes, special skills, and other traits were randomly selected from among the suggestions of 2channel users and consolidated into a single character, which would be shown as a prank for April Fools' Day. On 6 April 2008 she appeared for the first time on video, and on 13 April 2008, the first voicebank for Teto was released, with Oyamano Mayo as the voice provider. The first song using her voice was released on 1 June 2008. The rights holders who provided the character design and voice of Kasane Teto established the circle "TWINDRILL" in 2009 to promote and manage the character. Although Kasane Teto was a

parody A parody is a creative work designed to imitate, comment on, and/or mock its subject by means of satire, satirical or irony, ironic imitation. Often its subject is an Originality, original work or some aspect of it (theme/content, author, style, e ...

character of

Crypton Future Media , or simply Crypton, is a Japanese media company based in Sapporo, Japan. It develops, imports, and sells products for music, such as sound generator software, sampling CDs and DVDs, and sound effect, FX and background music, BGM libraries. The ...

's series of

Vocaloid is a singing Speech synthesis, voice synthesizer software product. Its signal processing part was developed through a joint research project between Yamaha Corporation and the Music Technology Group at Pompeu Fabra University, Barcelona. The s ...

singers, Twindrill organised the rights and established a cooperative relationship with Crypton from 2009 to 2010. Since 2010, Crypton has been the point of contact for commercial use.

2010s and 2020s

Teto continued to make an impact on the Vocaloid community, with many songs being released. In 2012, a DLC pack for Hatsune Miku: Project Diva F featured her. In 2013, she appeared as a part of Hatsune Miku's act in the

Sapporo Snow Festival The is a festival held annually in Sapporo, Japan, over seven days in February. Odori Park, Susukino, and Tsudome are the main sites of the festival. In 2007 (57th festival), about two million people visited Sapporo to see the hundreds o ...

Synthesizer V

For the 15th anniversary of Teto on 1 April 2023, Japanese software developer

AH-Software AH-Software is the software brand of AHS Co., Ltd. (original full name: Artist House Solutions Co., Ltd.), an importer of digital audio workstations and encoders in Tokyo, Japan. It is also known as the developer of Voiceroid and a number of Voca ...

announced they would be partnering with Twindrill and Crypton Future Media to produce a voice database for the character, its first full commercial release. For the occasion, a significant redesign was made, giving Teto a new outfit to stand apart from being a Hatsune Miku parody. The deep learning technology in Synthesizer V made use of singing from the voice provider rather than concatenative phoneme samples like UTAU. This allowed for cleaner, more natural synthesis and various features such as "Vocal Modes" for expression and the ability to sing in any language that Synthesizer V AI supports via "cross-lingual synthesis". Synthesizer V AI Kasane Teto was released on 27 April 2023, and has received frequent updates. A limited "lite" voice database for the same software was released soon after on 8 May 2023, available for free download.

VOICEPEAK

For Teto's 17th anniversary on 1 April 2025,

announced an adaptation of Kasane Teto's voice for their Japanese text-to-speech software, which was released shortly after on 24 April 2025.

Voicebanks

Reception

Despite not being a Vocaloid character, Kasane Teto has gained popularity among Vocaloid and UTAU fans. Within six months of her release, more than 500 videos with the "Kasane Teto" tag were published on

Niconico , known before 2012 as , is a Japanese video sharing service based in Tokyo, Japan. "Niconico" or "nikoniko" is the Japanese sound symbolism, Japanese ideophone for smiling. As of 2021, Niconico is the 34th most-visited website in Japan, accordi ...

, and the song (''Uso no utahime'', "A Fake Diva") featuring Kasane Teto reached 100,000 views, entering the Vocaloid Hall of Fame. According to stats from the 2025

Music Awards Japan The Music Awards Japan (abbreviated as MAJ), is a music awards show by the Japanese music industry to honour musical talents from Asia, Japan and the Western regions. The awards are organized by the Japan Culture and Entertainment Industry Promo ...

, 5 out of the top 10 most popular Vocaloid tracks in Japan featured Kasane Teto, notably surpassing Hatsune Miku who was featured in 3. Among songs nominated for the 2025 Best Vocaloid Culture Song award, Teto was the second most used voice behind Miku.

Notable songs

Other media

Kasane Teto has appeared in many different media, such as in

Sega is a Japanese video game company and subsidiary of Sega Sammy Holdings headquartered in Tokyo. It produces several List of best-selling video game franchises, multi-million-selling game franchises for arcade game, arcades and video game cons ...

music game A music video game, also commonly known as a music game, is a video game where the gameplay is meaningfully and often almost entirely oriented around the player's interactions with a musical score or individual songs. Music video games may take a ...

franchise '' Hatsune Miku: Project DIVA'', becoming a promotional character for

Hokkaido Broadcasting , also known as HBC, is a Japanese broadcast network affiliated with the Japan News Network (JNN), Japan Radio Network (JRN) and National Radio Network (NRN). Their headquarters are located in Hokkaidō. HBC was established on November 3 ...

, having

Nendoroid The series is a brand of plastic figures created by the Japanese Good Smile Company since 2006. They typically depict characters from anime, manga or video games and are designed with a large head and smaller body to give them a cute appearan ...

and other plastic figures from

Good Smile Company is a Japanese manufacturer of hobby products such as the Nendoroid and Figma (toy), Figma product lines, as well as scale figures. In addition to production and manufacturing, its business includes design, marketing and distribution. Its product ...

, performing with

Nakamura Shidō II , better known by the stage name , is a Japanese kabuki and film actor. Life Born in Tokyo, the son of kabuki actor Nakamura Shidō I, young Nakamura made his kabuki debut at the age of eight. He took the name Shidō the following year, followin ...

on the

Kabuki is a classical form of Theatre of Japan, Japanese theatre, mixing dramatic performance with Japanese traditional dance, traditional dance. Kabuki theatre is known for its heavily stylised performances, its glamorous, highly decorated costumes ...

stage, and having novel adaptations.

Notes

References

{{Authority control Internet characters introduced in 2008 Fictional singers Japanese idols Japanese popular culture 2008 software 2009 software 2010 software 2012 software 2015 software 2018 software 2021 software 2023 software 2channel April Fools' Day jokes 2008 hoaxes