Tsukaiban is a post in the Edo shogunate. In older times, it was also called tsukai-yaku. Under the command of the wakadoshiyori, the officer earned executive allowance of 500 koku (rice yield) and salary of 1,000 koku, was of Hoi (commoner) rank and was stationed to be at the side of the southern door of the Kiku-no-ma Hall.
The post originates from the function of the military officer in the Sengoku Period (Period of Warring States), who served as messenger and scout in the battlefield and messenger to the enemy army. The post stayed in the Edo shogunate. The post was made official in 1617, but except during the Shimabara Rebellion, never took part in major warfare and began to focus on surveillance of shogunate administrators such as ongoku-bugyo (the collective name of the magistrates placed at important areas directly controlled by the government in the Edo period) and daikan (governors) who executed shogunate policy in remote locations along with metsuke (inspectors).
Later, the officer became responsible for service as kunimetsuke (inspector of feudal domains), shokoku-junkenshi (envoy responsible for surveillance of the daimyo), supervision of shogunate administrators at Nijo-jo Castle, Osaka-jo Castle, Sunpu-jo Castle, Kofu-jo Castle, etc., as well as supervision of daimyo hikeshi (daimyo's firefighters) and jobikeshi (firefighters under the direct control of the Edo shogunate) in case of fire outbreak in Edo.
The number of such officers was believed to be 28 (or 25, according to some sources) in the Genna era and was gradually increased to around 50 in the Bunka era, shooting up to 112 in the last years of the Edo Period. For this reason, the number was halved to 56 in 1866, and salary was revised in the following year, with executive allowance kept at 500 ryo (gold pieces) for those earning more than 1000 koku and half the amount for lower-rank earners.
In addition, there was the otsukaiban in O-oku (the inner halls of Edo Castle where the wife of the Shogun and her servants reside), who served as liaison officer between the Midaidokoro (wife of the Shogun) or other high-ranking woman servants and the shogunate administrators.