Cromartie High School is full of interesting students: one looks like Freddie Mercury and walks around silent and shirtless, one is a robot (although no one ever seems to notice), while another, perhaps the smartest of the bunch, is a gorilla. Takashi Kamiyama, an honors student who ends up in this lowest-of-the-low high school, stands out because he is just an ordinary teen, and much of this early volume of the manga series deals with him trying to make sense out of the nonsense around him.
This manga is a parody of the Japanese "yankii" (juvenile delinquent) comics that were popular in the 1970s and 1980s. It is written and drawn by Eiji Nonaka, which is not his real name but an alias. The author is purportedly a gag writer who does frequent fill-in stories, but that is merely speculation. Whoever he may be, he draws in the style of Ryoichi Ikegami, a legendary artist who worked on such seminal works as Crying Freeman and Mai the Psychic Girl.
There are a great number of popular culture references in the series, from the names of the local high schools (they are all last names of non-Japanese professional baseball players, such as Warren Cromartie and Orestes Destrade), to rock music, and professional wrestling. Much of the self-conscious humor comes from verbal riffs, situational comedy, and a meta-awareness of the manga itself (for example, the author fully admits that Mechazawa is just there as a cheap ploy to skew younger and get more boy readers who are into robots).
Aside from the 17 volumes of the manga (13 of which are available in English, from the publisher ADV Manga), Cromartie High School has also branched out into other media, including an anime series as well as a live-action movie (a review of the movie version can be found here).
While some restructuring issues at ADV have plagued the release dates of the manga, many fans can still enjoy clips from the television show on YouTube. Here are a sampling of what's out there: the catchy opening theme, Episode one, which includes much of what is portrayed in volume 1 of the manga, and a scene with Mechazawa Beta, Mechazawa's "little brother."