After Tokyo was destroyed by an earthquake and rebuilt by Genom, Voomers (VOodoo Organic Metal Extension Resource), advanced robots, became commonplace. Although Voomers took care of most of the manual labor, they could malfunction and become Boomers. Boomers are crazed robots that are often involved in violent and criminal activities, running rampant and destroying everything in their path, whether by malfunction or sabotage.
The Advanced Police (often simply called A.D. Police) was created to counter Boomer threats. They are Genom City's anti-robot crime division, specially trained to deal with Boomer-related situations. Members of the police who patrol the city and actively hunt Boomers are nicknamed "Fronters" and are split into "Fronter Groups" - squadrons. After the Knight Sabers were created, the two group would often work together to stop Boomers.
Fire Bees were used for quick mobilization against high-speed targets, as well as reconnaissance and surveillance.
An elite branch of the A.D. Police literally called Branch that worked behind the scenes of the A.D Police and dealt with special cases. Officially, it didn't exist and couldn't be prosecuted for any actions it took. It often clashed with the main body of the police as the Fronters saw Branch operatives as always getting in the way, taking on rogue Boomers in Fronter jurisdiction as a form of glory hunting. Many found their presence, a shadowy group with a separate agenda and no clear accountability, distasteful.
Branch was better equipped to handle larger threats though, such as the distribution and producers of a drug that caused Voomers to turn into Boomers, the Sex Boomer Crusher, and Kenji Sorime after he caused a chain explosion across the city. Members routinely infiltrated large companies such as Genom to covertly check for fraud and corruption. The "watchers in the dark", they also found and dealt with corrupt individuals within the A.D.
A.D. Police seemed to have two different alerts for Boomers. One was Sequence N, which referred to the "Nano-Stampede" some Boomers went on. They would go about and fuse themselves to anything mechanical nearby, growing larger and stronger as time went on. They also became harder to kill, so had to be eliminated very quickly. This alert was heard only in A.D. Police: To Protect and Serve.
Sequence B involved the Voomer in question breaking down and becoming a Boomer, attacking anything in a seemingly random manner. Typically, Sequence B alerts involved a large blue combat Boomer and were heard only in Bubblegum Crisis and Bubblegum Crash.