On December 25, 1887, Mishima as Superintendent General brought to execution the Regulations for the Preservation of Law and Order declared publicly by imperial edict, which aimed to remove so-called "dangerous characters" from the imperial circles and opposed Freedom and People's Rights Movements such as the (三大事件建白運動 Sandai Jiken Kempaku Undō) and the United Front Movement. He was also the Superintendent General of the Metropolitan Police who brought to execution the Public Order & Police Law of 1900, the predecessor to the Peace Preservation Law of 1925.