UTAU is a freeware singing synthesis program. It is much like Vocaloid in usage, in that a user can input phonemes and change notes to create singing vocals. UTAU voicebanks are often personified with anime or cartoon-styled avatars.
UTAU XYZ was founded in July 2009 by MystSaphyr, starting with the creation of the UTAU Kikyuune Aiko. The UTAU XYZ Youtube account is mostly maintained by Myst and Acorn (voicer of the second UTAU in the series, Mathieu Rosaire)