Yuuko Ishibashi (石橋優子, Ishibashi Yūko) is a Japanese singer, born April 3, 1980 in Tokyo, with a 4 octave vocal range. She is most well known for her vocal performances in Gust-produced video games such as the Ar tonelico series and Atelier Iris 3: Grand Phantasm. She has also performed in various Japanese television advertisements and events, theater, and children's programmes. Her debut album Haruka naru Toki no Utagoe was released January 2008.