National Police Agency (Japan) in the context of "Police officer"

The Home Ministry (内務省, Naimu-shō) was a Cabinet-level ministry established under the Meiji Constitution that managed the internal affairs of Empire of Japan from 1873 to 1947. Its duties included local administration, elections, police, monitoring people, social policy and public works. In 1938, the HM's social policy was detached from itself, then the Ministry of Health and Welfare was established. In 1947, the HM was abolished under the Supreme Commander for the Allied Powers restoration, then its administrative affairs were proceeded to the National Police Agency, the Ministry of Construction, the Ministry of Home Affairs and so on. In 2001, the MOHA was integrated with the Management and Coordination Agency and the Ministry of Posts and Telecommunications, then the Ministry of Public Management, Home affairs, Posts and Telecommunications was established. In 2004, the MPHPT changed its English name into the Ministry of Internal Affairs and Communications. In other words, the MIC is the direct descendant of the HM.

A special organization (特別の機関, Tokubetsu no kikan) is a Japanese government organization established under the Cabinet Office, ministries or their external organs (commission and agencies) when particularly necessary. It is distinguished from a facility. The classification was created when the amendments to the National Government Organization Act [ja] were promulgated on July 1, 1984. The amendments, in particular, made it clear that the National Police Agency is an extraordinary organ attached to the National Public Safety Commission, which is an external organ of the Cabinet Office.

Riot Police Unit (機動隊, Kidō-tai) are the rapid reaction forces of Japanese prefectural police. These units are not only riot police, but a type of emergency service unit to maintain public order against large civil disorder, disaster response, or other emergency situations as the key units of Japanese law enforcement for crisis management. They are operated by prefectural police headquarters (PPH) under the supervision of the Security Bureau of the National Police Agency (NPA).

In the law enforcement system in Japan, prefectural police (都道府県警察, todōfuken-keisatsu) are prefecture-level law enforcement agencies responsible for policing, law enforcement, and public security within their respective prefectures of Japan. Although prefectural police are, in principle, regarded as municipal police, they are mostly under the central oversight and control of the National Police Agency.

As of 2020, the total strength of the prefectural police is approximately 260,000 sworn officers and 28,400 civilian staff, a total of 288,400 employees.