Like the Shinsengumi, the Mimawarigumi too was a special police force, created to restore order to Kyoto. The Mimawarigumi were made up of higher-ranking samurai and retainers who served feudal lords, as opposed to the Shinsengumi which consisted of ronin. In Gintama, the Mimawarigumi appeared wearing the opposite color uniforms from the Shinsengumi, white. The group served as grand rivals to the Shinsengumi as the had since the Baragaki Arc get in their way of work within the laws. However after a grand fight between them both in the Farewell, Shinsegumi Arc, The mimawarigumi joins hands with the shinsegumi as a united police force to fight againts the coruppted Bakufu and the Tendoshu.
There are only two named members of Mimawarigumi; Sasaki Isaburo, the commander of Mimawarigumi and the vice captain Imai Nobume, Imai Nobume is a female member and a part of the assassination unit of the Mimawarigumi. However after the death of the commander and the absense of the vice-captain, the group joins the rebel alliance under Kondo Isao"s command.
The mimawarigumi first actions in the series was when Sasaki deploid them for the disposal of the terrorist group Check Out Gang. However since the terrorist group had taken Testsunosuke as hostage, the Shinsegumi stands in the way of their duties as Sasaki would dispose of them no matter what would happen to his half brother. However, once Testunosuke had been saved by Gintoki and the Shinsegumi, The mimarigumi arrested the terrorsit group without further fightning with ther rivals.
The Mimawarigumi is latter deployed to guard the Shogun"s castle do to recent assassination on high-class members of the shogun family. Sasaki later on together with the Mimawarigumi saves Gintoki and his friends from the Naraku Faction that was deployed by Tokugawa who was the one behind the assassinations of the family. After arresting Tokugawa towards the end the mimarigumi contiune thereafter protecting the castle from threats of the Hitotsubashi Faction.
The mimawarigumi were they one responsible for arresting Ikeda Yaemon for her treason againts the Ikeda family and got her send out in a corpse cargo ship.