Not a real vocalist, but a synthesized singer, created through the collaborative efforts of volunteers on the internet who shared ideas and concepts.

Kasane Teto was created as an April Fool's joke in March 2008 within the anonymous forum 2channel. She debuted as a "fictional VOCALOID" on the video-sharing site Niconico Douga. Later, through the vocal synth tool "UTAU", unique vocal samples were created, and she began her journey as a virtual singer capable of singing like a VOCALOID.
Today, numerous fans create various works featuring Teto daily, including illustrations, songs, and videos.

Her original character design was created by Sen, while her vocal materials were provided by Mayo Oyamano [小山乃舞世].