Kasane Teto

Biography

Kasane Teto began not with a label debut but with a fictional VOCALOID collectively devised on Japan’s 2channel forum in March 2008 for April Fools’ Day. Revealed on 1 April, she had original art by Sen and voice recordings and processing by Oyamano Mayo. The official account states that she is neither a Yamaha/Crypton VOCALOID product nor a pitch-shifted Hatsune Miku. [3] [4]

The joke developed into usable singing material. The official chronology records a first UTAU-and-Teto singing video on 6 April 2008 and Mimirobo-P’s original 耳のあるロボットの唄 on 10 June. TWINDRILL, formed on 1 July 2009, provided an ongoing organization for managing the character. [5] [6]

Community songs also reached commercial releases: ゴジマジP’s おちゃめ機能 -Full ver.- appeared on an EXIT TUNES compilation in September 2010. The official site explains that 嘘の歌姫 dramatizes events and that its story of the original community abandoning Teto is false. [5] [3]

On 27 April 2023, AHS released Synthesizer V AI 重音テト, a new AI singing database based on Oyamano Mayo’s voice. Creators use editing software to produce songs and vocal performances. The official site still offers the UTAU voice libraries and also lists a VOICEPEAK text-to-speech product, giving the character distinct singing and speech tools. [7] [8] [9] [6] [13]

She also appears as a digital stage performer. A live video published by the official Hatsune Miku channel documents Teto’s guest appearance at the evening Zepp Haneda show on 3 May 2025, performing サツキ’s メズマライザー with Miku. It credits the songwriter and character rights holders and identifies the Synthesizer V Teto version. [10]

On 11 February 2026, Tokuma Japan released the TWINDRILL-produced compilation 0401 - The Best Days of 重音テト 2026. It brings together different creators’ works using Teto’s voice, including 柊マグネタイト’s テトリス, サツキ’s メズマライザー, 吉田夜世’s オーバーライド and 原口沙輔’s イガク. [11] [12]

[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]

Milestones

1. 2008-04-01
   April Fools character revealed [5] [3]
2. 2008-04-06
   First UTAU-and-Teto singing video published [5]
3. 2009-07-01
   TWINDRILL formed [5]
4. 2023-04-27
   Synthesizer V AI edition released [8] [7]
5. 2025-05-03
   Performed メズマライザー with Miku at Zepp Haneda [10]
6. 2026-02-11
   Official 0401 compilation released [11]

Works & performances

• 耳のあるロボットの唄 — 耳ロボP2008
• おちゃめ機能 -Full ver.- — ゴジマジP2010
• メズマライザー — サツキ / 初音ミク・重音テト, Zepp Haneda live2025
• 0401 - The Best Days of 重音テト 20262026

Sources

1. Kasane Teto official websiteAccessed 2026-10-20
2. Tokuma Japan: Kasane Teto profileAccessed 2026-10-20
3. TWINDRILL: Kasane Teto origins, creators and historical clarificationsAccessed 2026-10-20
4. TWINDRILL: preserved history, character creationAccessed 2026-10-20
5. TWINDRILL: official Kasane Teto chronologyAccessed 2026-10-20
6. TWINDRILL: UTAU voice librariesAccessed 2026-10-20
7. AHS: Synthesizer V AI 重音テト announcement, 3 April 2023Accessed 2026-10-20
8. AHS: 2023 release history, 27 AprilAccessed 2026-10-20
9. AHS: Synthesizer V AI 重音テト productAccessed 2026-10-20
10. Hatsune Miku official channel: メズマライザー, Zepp Haneda 3 May 2025 live recordingAccessed 2026-10-20
11. Tokuma Japan: 0401 - The Best Days of 重音テト 2026, regular edition TKCA-75309Accessed 2026-10-20
12. Tokuma Japan: 0401 compilation credits and track announcementAccessed 2026-10-20
13. TWINDRILL: VOICEPEAK text-to-speech productAccessed 2026-10-20

Checked on 2026-10-20. 2008-04-06 is verified as a singing-video date, not the first voicebank distribution. Early history relies mainly on the rights manager’s preserved chronology; contemporary records can be added. All four versions received a second AI self-review by the original editor, without independent native-language editing.