Japan is a union of prefectural governments, each of which maintains its own police departments under the nonbinding guidance of the National Police Agency (NPA). NPA is an administrative, rather than investigative, organization. Training is standard nationwide. Curriculum for female officers includes traffic control, giving directions, meeting people, and report writing. Male officers receive standard training and learn to handle various firearms. Medical and disability insurance are thorough and complete. The major cause of injury is traffic accidents, usually to officers directing traffic. The police box system rotates officers, usually first year patrolmen. After a year of constantly supervised police box duty, newly commissioned officers return to the academy for 3 months of additional training. Police box officers must make biannual house visits to consult with community members. These visits result in a census of the community and help residents to organize neighborhood watch groups. Japanese police use bicycles more than autos or motorcycles, due to the congestion in cities. The policy on weapons is to keep them in a locked safe at the station when the shift is over rather than with the police officer. In the event an officer is suspected of misconduct, the department assumes full liability. Japan's tradition of familial interdependence is the glue that holds the police system together and in turn binds the system into the community.