K-ON! Original Soundtrack (「けいおん!」 オリジナルサウンドトラック(おりじなるさうんどとらっく) K-ON! Original Soundtrack) is the first "Original Soundtrack" (OST) of the anime K-ON!. The album contains 36 instrumental songs that are used as background music during the first season of the anime. It was released on 3 June 2009 in Japan by Pony Canyon. The whole album was composed, arranged and recorded by Hajime Hyakkoku.