The series follows the violent exploits of the toughest cop in the NYPD's 34th Precinct, "Sleepy" John Estes—known to his enemies as "Mad Bull"—and his partners, Daizaburo "Eddie" Ban and Perrine Valley.

After graduating from the New York City Police Academy, Japanese American NYPD rookie Daizaburo "Eddie" Ban is assigned to the 34th Precinct, which has the highest crime rate in Manhattan.

There, he is paired with Afro-Puerto Rican cop John Estes, who is nicknamed "Sleepy" by his friends but is notoriously known as "Mad Bull" by criminals due to his violent behavior.

Sleepy's actions are outrageous and illegal, but he always has the right motives (for example, he uses the money he skims off prostitutes to support venereal disease clinics and domestic violence shelters).

Written by Kazuo Koike and illustrated by Noriyoshi Inoue [ja], Mad Bull 34 was serialized in Shueisha's seinen manga magazine Weekly Young Jump from July 1985 to January 1991.