Honjin was a special lodging established in a post station of the main national roads in the Edo period (1603-1868). It was built for use by daimyo, Hatamoto (direct retainers of the Shogun), government officials, Imperial envoys, Imperial family members, and Monzeki (Buddhist priests of aristocratic or imperial lineage). The word “honjin” originally means the camp or field headquarters of a general from the late Heian period to the early Edo period. Later on, accommodations for a general were also called honjin, and then it was diverted to lodgings for travelers of high social rank.

In most case, the proprietor of general office managing a post station (Toiya) or the village head officer (Nanushi) was appointed to be the proprietor of a honjin. Those who owned honjin were not warriors but they were given the privilege of wearing swords and a surname (myoji taito). They were also allowed to build the gate and the entrance porch for their private area.

The site where Honjin was built usually had an area of more than 3,300 sq m, and the main building was built in accordance with formalities, which included the Onarimon Gate and the raised room (Jodan-no-ma) as the main guest room. Presently, there are 13 honjin existing and open to the public. Among them, the largest is the honjin at Kusatsu-juku post station on the Tokaido Road. With as many as 39 rooms, a building area of 1706 sq m, and a site area of 4727 sq m, it is designated as a national Historic Site.