Oranges & Lemons 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 the opening theme ("Soramimi Cake") and closing theme ("Raspberry Heaven") to the anime series Azumanga Daioh.
Itō and Ueno, still under the title of Oranges & Lemons also performed the album "Tribute to Azumanga Daioh" in which they sang multiple songs based on the music from the series. This album is notable because it not only contains an alternate 'softer' version of "Soramimi Cake", but also an a cappella version of "Raspberry Heaven".

Read more about Oranges & Lemons on Last.fm.