how is the law enforcement in the country?
It is provided mainly by the prefectural police departments, under the oversight of the National Police Agency and supervised by the Criminal Affairs Bureau of the National Police Agency.
Japan
Domestic security in Japan is provided mainly by the prefectural police departments, under the oversight of the National Police Agency and supervised by the Criminal Affairs Bureau of the National Police Agency. 
what is the type of government in japan It is the central government of Japan is the country ruled by the emperor or the prime minister? The Prime Minister what is the role of the emperor there then? His role is ceremonial and he has no powers related to Government. what is service period of the prime minister there? four years what divisions of ministries can we find there? UNANSWERABLE
wiki:7760061
Japan [SEP] Domestic law enforcement
Domestic security in Japan is provided mainly by the prefectural police departments, under the oversight of the National Police Agency and supervised by the Criminal Affairs Bureau of the National Police Agency. As the central coordinating body for the Prefectural Police Departments, the National Police Agency is administered by the National Public Safety Commission. The Special Assault Team comprises national-level counter-terrorism tactical units that cooperate with territorial-level Anti-Firearms Squads and Counter-NBC Terrorism Squads. Additionally, there is the Japan Coast Guard which guards territorial waters. The coast guard patrols the sea surrounding Japan and uses surveillance and control countermeasures against smuggling, marine environmental crime, poaching, piracy, spy ships, unauthorized foreign fishing vessels, and illegal immigration.