She is a young girl with red eyes and redtwin drills. She typically wears a dark blue/gray outfit with red trim. Her official profile lists her as a "chimera", so she is sometimes given characteristics like a forked tail or wings. Her character item is a baguette.
She was created as an April Fools joke by the VIPPERs of 2ch, meant to trick Nico-Nico Douga users into thinking she was the 3rd Vocaloid from Crypton. After the joke was over, instead of fading into obscurity Teto was picked up by UTAU, a freeware knock-off of VOCALOID. She has maintained a level of popularity, and many have tried to replicate this effect with other joke and fanmade characters since.
After her 15th anniversary on April 2023, she received an updated voicebank under the Synthesizer V engine, which would boost her popularity even further.
Oyamano initially used the name Oyama Nobuyo as a reference to famed singer and voice actress Ooyama Nobuyo. Since the latter is most known as the voice of Doraemon, fans had Teto share similar traits. Teto's catchphrase 君は実に馬鹿だな ("You really are an idiot, aren't you?") also originated from a Doraemon comic.
Do not tag Kasane Teto as a VOCALOID. She is either an UTAU or a SynthV.
