Doshin (patrol officer) (同心)
The term "doshin" refers to one of the low-level officials of the Edo bakufu (Japanese feudal government headed by a shogun). They served in a public office to conduct general affairs and police work as a subordinate of police sergeant under the control of magistrates, Kyoto deputies, castle keepers, captains of the great guards, head castle guards and others. Also, a lot of domains officially named ashigaru-level soldier (common foot soldier) under the direct control of the domain as doshin.
Summary
Well-known doshin officials are Machikata-doshin, who handled justice, administration, and police affairs in Edo under the town magistrate, and Sanmawari-doshin, who conducted patrols of the town. Machikata and Mawarikata-doshins as well as doshin under the investigation division for arson and organized robbery often used their private pawns called okappiki or meakashi as an investigation assistant and information source. In the light of the above, okappiki and meakashi were only private servants of a doshin, not proper members of the town magistrate's office, although they are sometimes regarded as present-day police officers. Rather, it can be said that doshin corresponds to a modern patrol police officer.
Originally, the word "doshin" meant "solidarity" during the late mediaeval period in Japan, and it was a synonym of "accomplice" or "insurgence." In the Sengoku Period (Period of Warring States), vassals (lower-ranked samurai) of a warring lord came to approach matters in unity in order to perform service at ordinary times and do military service for their master's house. This made it common to call lower-ranked samurai "doshin," and subsequently, the Edo bakufu decided to use it as one of official titles of the shogun's retainers.
Since all the foot soldiers of the Tokugawa clan's immediate retainers became doshin when the Edo bakufu was established, various sorts of doshin were made; for example, Iga doshin and Koka doshin descended from ninja, a one-hundred matchlock infantry unit, Hachioji thousand doshin of country samurai, and so on. Those who became a doshin in the early Edo period were specially called "fudai" (hereditary vassal), and even if they lost their official titles, they were still entitled to receive salary and could leave this to their descendants. Doshin of the bakufu were not hatamoto (direct retainers of the bakufu) but bakushin (shogun's retainers), which were in the gokenin (shogunal retainers) class, and upper ranked doshin received an eighty-koku (crop) salary and a ration for five persons, which means they substantially had a hundred-koku income approximately. Their salary was equivalent to that of a senior vassal of a feudal lord who had ten thousands- koku crop yields.
Yoriki (police sergeant) under the control of the town magistrate and many of doshin were given their residence (which was like modern police quarters) in Hatchobori (Chuo Ward, Tokyo Prefecture), which was often used as a byword for doshin. In addition, a residence given to a yoriki was about 990 square meters and a residence given to a doshin was about 330 square meters. Since their job was disliked as it was so-called a dirty job, they formally employed a new person when his predecessor left his office although it was substantially hereditary. Lower ranked doshin such as prison patrol doshin just received a ration for five persons, but in reality they had real handsome income as they received bribes from territorial lords and merchants, so they could afford to hire some private servants such as okappiki and meakashi (thief-takers).