Japan National Police Wiki

Japan's national police force. Unlike the national police from various other countries, they do not have jurisdictions of their own. They are instead responsible for supervising every prefectural police department in the country.

There have several identifying characteristics:

Their police cars are painted white on the top and black on the bottom. Their emergency lights are red.
Their buses, trucks and helicopters are painted blue.
Their police uniforms are either a blue shirt and blue pants or white shirt and blue pants.
Some officers wear blue vests, some others wear blue jackets. Some officers may wear a blue necktie as well.
Some officers wear a green armband on their left arm.
Female police officers wear a round police hat.