Kawaji Toshiyoshi , also known as Kawaji Toshikane, was a Japanese military general, politician, and samurai. during the Meiji period. A Satsuma Domain samurai initially tasked to study foreign systems for application in the Japanese military, Kawaji fought against forces loyal to the Tokugawa shogunate during the Boshin War. Later, his work on setting up the Japanese police at the aftermath of the Meiji Restoration, first as rasotsu, and then as keisatsu, earned him the recognition as the founder of Japan's modern police system . Besides his police and military work, he was also noted for his contributions to the development of Kendo, a Japanese martial art.

The Tokyo Metropolitan Police Department (TMPD) , known locally as simply the Metropolitan Police Department (MPD), is the prefectural police of Tokyo Metropolis, Japan. Founded in 1874, the TMPD is the largest police force in Japan by number of officers, with a staff of more than 40,000 police officers and over 2,800 civilian personnel.