K-On! Is a Japanese four-panel comic strip manga who is written and illustrated by Kakifly. The manga was first initially serialized by Houbunsha (a Japanese publishing company) in the magazine Manga Time Kirara between the May of 2007 and October 2010, then the manga was relaunched in April 2011 with two separate storylines in Manga Time Kirara, and also Manga Time Kirara Carat. Then, a 13-episode anime was adapted and produced by Kyoto Animation between April and June 2009, and later a 26-episode second season (K-On!!, with an extra exclamation mark) aired the following year. The title of the series come from keiongaku, the Japanese word for light music, but in the Japanese context is equivalent to pop music.
K-On! Is about four Japanese high school girls, later 5, who join Sakuragaoka Girl’s High School’s light music club to save it from being completely terminated altogether. Unfortunately, they are the only members of the club, including Yui Hirasawa, the main character, who has no experience whatsoever playing musical instruments and has an inability to read sheet music. Eventually, she becomes an excellent guitar player. Since then, the other members of the club Mio Akiyama (bassist), Ritsu Tainaka (drummer), and Tsumugi Kotobuki (keyboardist) spend their school days practicing, performing, and hanging out. The club is overseen by their teacher Sawako Yamanaka. In the second year of high school, the club welcomes another member, underclassmen Azusa Nakano (rhythm guitarist). Soon after she joins, the club becomes more structured and they begin to practice more.