Heart of Air is a Japanese duo formed by 伊藤真澄 (Masumi Itō) and 上野洋子 (Yōko Ueno). The duo is most notable for performing "Blue Flow", the closing theme to the anime series Haibane Renmei. Itō and Ueno have also formed the group Oranges & Lemons for the Azumanga Daioh soundtrack. Read more on Last.fm