In the 12th year of the Keichoera(1607), the first Joseon envoys of the Edo period visited Sumpu and Sumpu Castle. The HaeSaRok, written by vice-envoy GyeongSeom, contains descriptions of Sumpu and Sumpu Castle at the time. Acomparison of the descriptions in HaeSaRok and Japanese historical records of Sumpu Castle’s construction process shows many consistencies and HaeSaRok can be considered a valuable document, describing the state of Sumpu and Sumpu Castle at the time. Although the castle was still under construction, it is noteworthy that the buildings necessary to meet foreign envoys, such as the mon (gates) and the goten (palace), were already in place. Sumpu Castle employs a rinkaku-shiki layout in which three kuruwa (bailey, precincts and compounds that make up the castle grounds) and three moats are alternately arranged from the center outwards. The castle was built twice: once in the Tensho era (end of the 16th century), and once in the Keicho era (beginning of the 17th century). It survived into the Meiji period while undergoing restoration from fire and earthquake damage. The area was subsequently used for such things as army barracks, government offices, and schools before, following World War II, the center of the castle became a park where visitors can soak in the area’s history. During an excavation survey of the stone base of the tenshu (tower keep) in 2016, relics of the medieval Imagawa clan were discovered, along with the stone bases of the tenshu from the Tensho and Keicho eras. In particular, surveys of the Keicho-era tenshu’s stone base yielded three results. Firstly, details such as the size of the entire stone base and the characteristics of its ishigaki (dry stone walls) were revealed. Secondly, the rear surface of the ishigaki and the structure of the foundations were revealed. Thirdly, traces of the castle’s construction and restoration processes were confirmed. From the results of excavations and other facts it is clear that the tenshu of the Keicho-era Sumpu Castle was exceptionally large in scale and unique in structure compared to other castles. Considering this, along with the castle’s other characteristics, it is fair to say that Sumpu Castle was an exceptional castle. It is indicative of the castle’s suitability as a symbol of Tokugawa Ieyasu’s government in Sumpu. We can see that Sumpu and Sumpu Castle were places of great importance that served as the stage for restoring diplomatic relations between Japan and Joseon, just as Ieyasu was establishing his government.
