The series title comes from the Japanese word Keiongaku, which could be translated into French as "soft music/pop". The first season anime's opening theme is "Cagayake! Girls" by Aki Toyosaki with Yoko Hikasa, Satomi Satou and Minako Kotobuki. The ending theme is "Don't Say 'Lazy'" by Hikasa with Toyosaki, Satou and Kotobuki.
The history of K-On! revolves around four Japanese students who join the club of pop music school, to ensure that it is not disbanded for lack of members. However, the four are the only members of the club, and one of them, Hirasawa Yui, has no experience in using either a musical instrument or read music.