Yukio, known by his friends as "Koyuki", is a regular 14-year-old Japanese boy who enters junior high school with two childhood acquaintances. One is now a useless pervert, and ironically the other is a highly sought after female student. Koyuki's boring life is changed when he saves an odd-looking dog, named Beck, from some kids. Beck's owner turns out to be an emerging rock musician, Ryuusuke Minami. The two become friends and their crazy, fun, and sometimes dangerous music adventure begins.

The story focuses on the trials and tribulations of their punk and rapcore band named BECK. There's also an important subplot that deals with Koyuki's relationship with Ryuusuke's sister, Maho.