(My apologies, I can't understand Japanese very well yet...)
Kakou is a Native American-themed (ネイティブアメリカン) Overseas UTAU. She was created in November 2009. Read more about her here: http://utau.wikia.com/wiki/Kakou_Higure
Permission is granted to use artwork for promotional purposes. I hope to see uses for Kakou in the future!