Military police, or "MPs" are a unit in the most nation's militaries, including the Japan Self-Defense Forces responsible for law enforcement on military bases and installations. They are typically recognized by the acronym "MP" on their uniforms, in the case of JSDF MPs in the Special Region, on an armband.
The first, and thus far only JSDF military police unit garrisoned in the Special Region is based at Alnus, and whose jurisdiction includes both the military base and the Alnus refugee camp. At Alnus, JSDF MPs are equipped with standard-issue JSDF uniforms, but with armbands marked with the letters "MP". They are armed with Minebea P-9 handguns in standard issue holsters.
As the refugee camp increased in population, to the point of becoming a town in its own right, the JSDF MPs found themselves undermanned. In order to cope with the increasing population of the base, the JSDF recruited the Alnus Mercenary Brigade from among the local population. These auxiliaries wear the same "MP" armbands as regular JSDF MPs, but are otherwise dressed in privately purchased armor or other clothing typical of the Special Region. Auxiliary MPs are armed with a variety of, presumably privately purchased weapons typical of the Special Region, including swords, polearms, bows, and crossbows.
The Military Police in Alnus are periodically seen during scenes of the city. Most notably, Rory Mercury and Myuute Luna Sires are known to serve as auxiliary MPs. It is mentioned that the MPs dealt mostly with offenses such as petty theft and minor assaults such as bar fights. Special Region offenders are typically sentenced to terms of hard labor aiding in the reconstruction of Italica after the siege, on arrangement with the Formal Clan, while Japanese offenders are tried, sentenced, and, if convicted, imprisoned in Japan.
The only known violent crime that has occurred in Alnus was the Assassination Attempt on Noriko Mochizuki. MPs were among the JSDF personnel who responded to the incident, thought at that time, both Lt. Akira Yanagida and Delilah were already wounded and quickly rushed to the hospital.