)[c] is a Japanese anime television series based on the manga of the same name written and illustrated by Kakifly.

(with two exclamation marks), aired in Japan between April and September 2010, with an OVA episode released in March 2011.

[3] The episodes began airing on subsequent networks at later dates which include BS-TBS, MBS, and CBC.

An additional original video animation (OVA) episode was released with the final BD/DVD volumes on January 20, 2010.

Both an English-subtitled and English-dubbed version by Red Angel Media began airing on March 16, 2010, on Animax Asia.

[8] The series was released over four volumes in standard and limited editions for each format[9] starting on April 26, 2011.

[10] Bandai released the full first season on DVD under their "Anime Legends" line on February 7, 2012.

[14] Sentai Filmworks has licensed the first season and re-released the series on DVD on September 23, 2014, and currently streams on its HIDIVE platform.

[18] At the Let's Go live concert in Yokohama, Japan held on December 30, 2009, a second season was announced for production.

[25] Developed as an original story, it was produced by Kyoto Animation with Naoko Yamada as the director.

[26][27][28] The film features the two songs "Ichiban Ippai" and "Unmei wa Endless" by Aki Toyosaki.

The film opened at #2 with a gross of ¥317,287,427 (US$4,070,919) from 137 theaters,[29] and has earned a total of ¥1,639,685,078 (US$21,419,792) by the end of its run.

[34] The first Japanese DVD volume of the anime series sold around 8,000 copies to debut seventh in the ranking on the Oricon charts for the week of July 29, 2009.

[37] The Blu-ray Disc release of the first volume sold about 33,000 copies in the same week, to top the Oricon BD charts.

was the top-selling anime television Blu-ray Disc in Japan, having surpassed the previous record holder Macross Frontier, which sold approximately 22,000 copies of its first volume.

[41] In 2011, Sharp and Bandai announced plans to jointly launch a calculator with designs of the characters from K-On!.

Matthew Li of Anime Tourist described the exhibit as, "A place that genuinely understands its fanbase and carries all the sentimental props one can remember from the show and more; housing items seen in the school, like a museum.