I think you will not face a situation calling police in Japan. Luckily I have not called the police yet either. By the way, the telephone number of the police is 110 and Fire brigade is 119. By the way, the ambulance is also 119, therefore if you dial 119, the operator will ask you if you need an ambulance or it is a fire.
Top of the Japanese police force is National Police Agency which is controled by National Public Safety Commission and NPA is under Cabinet Office. However NPA does not have their own police stations in each prefectures. Each prefecture has its own prefectural police department and due to there are 47 prefectures in Japan, there are 47 prefectural police departments in Japan including Tokyo Metropolitan police department which covers the whole Tokyo Metropolis.
Then, each prefectural police department has several police stations in its area, Tokyo MPD has 102 stations throughout Tokyo, including in Chichijima island of Bonin(Ogasawara) islands. Then, not only police stations, each police station has several Koban; a police box and Chuzaisho; residential police box.
Japanese police is known that they have special investigation bureau against organized crimes and they are now keen on fraud against elderly people. Nationwide concern is that many elderly Japanese are involved in fraud that unknown men are calling their home and acting like their sons or grandsons. These criminals beg or force the innocent people to give their precious money to the criminals which are assumed to be connected with gangsters and Japanese mafia; yakuza.