Kasane Teto Day

What Is Kasane Teto Day?

October 10th is "Kasane Teto Day." Reading "10, 10" as "ten-tō" echoes the name "Teto," and the day is said to be celebrated every year by fans and the official team alike. Kasane Teto was born on April 1, 2008 -- April Fools' Day -- as a fictional voice synthesizer character created on the Japanese online message board 2channel. Her official profile birthday is April 1.

A "Lie" That Became a Singer

Kasane Teto was created as a joke riding the VOCALOID boom led by Hatsune Miku, posing as a fictional "third VOCALOID."

• Origin of the date: a wordplay reading "10, 10" as "ten-tō," echoing "Teto"
• How the character came to be: board users pitched ideas for her name, hairstyle and other traits, and she was revealed as a fake "upcoming product"
• Singing for real: soon afterward, volunteers made her voice usable in the free singing synthesizer "UTAU," and she became known as the "Singer of Lies"

A Major Comeback 15 Years Later

The holders of her design and voice formed the circle "TWINDRILL" in 2009 to manage and promote the character. In 2023, a voicebank for the commercial singing synthesizer "Synthesizer V AI" was released, and new songs using Kasane Teto have appeared one after another. Some have reached No. 1 on Niconico's VOCALOID song rankings, bringing her renewed attention.

Tips for Marking This Day

• Enjoy songs or artwork featuring Kasane Teto
• Look into the story of how Teto was born
• Explore the world of singing synthesizers such as UTAU and Synthesizer V
• Take the day to celebrate a favorite character of your own

A Joke That Captured Many Hearts

A character born from an April Fools' joke became able to sing for real through the work of fans and creators, and more than 15 years later she is still producing new hits. October 10th is a day to enjoy Kasane Teto, with her one-of-a-kind origin story, together with fans.