Kasane Teto is a fictional character from the voice synthesizer software UTAU, which allows users to create singing vocals from pre-recorded samples. Originally created as an April Fools' joke, she quickly became a beloved icon in the vocal synthesis community. Teto is depicted as a girl with long, twin-tailed red hair and a playful personality. Despite her origins as a prank, she has earned a significant fanbase and is often used in various musical and multimedia projects. Her unique voice and charming design have solidified her status as a beloved virtual singer.