K-On! (????!, Keion!) is a Japanese four-panel comic strip manga written and illustrated by Kakifly. The manga started serialization in Houbunsha’s seinen manga magazine Manga Time Kirara since the May 2007 issue, and also started a bimonthly serialization in Houbunsha’s magazine Manga Time Kirara Carat since the October 2008 issue.
A thirteen-episode anime adaptation produced by Kyoto Animation aired in Japan between April and June 2009. An additional original video animation episode was released in January 2010.
A second season will begin airing in Japan in April 2010 titled K-On!! (with two exclamation marks). The title of the series comes from the Japanese word for light music, keiongaku (????), but in the Japanese context is similar to pop music.
Source: Wiki
