[1][2][3][4] During the Edo period, the castle was headquarters of Sadowara Domain, which ruled portions of Hyūga Province (modern-day Miyazaki) from 1603 to 1871.

[6] The Itō clan claimed descent from Kudō Suketsune, who had been famously assassinated as per the events recounted in the Soga Monogatari.

As was common with mountain castles of the period, Sadowara Castle consisted of numerous enclosures, protected by earthen ramparts and dry moats, extending along the ridge of the mountain and making use of the natural terrain as part of its defenses.

An old illustration of castle shows there was three-story tenshu, and an archaeological excavation based on this picture found the ruins of its foundation in the inner bailey, along with that of a masugata-style compound gate.

Yoshihisa's younger brother, Shimazu Yoshihiro, who was also an accomplished and experienced general, served in the Western Army loyal to Toyotomi Hidetsugu at the 1600 Battle of Sekigahara.

The tenshu at Sadowara is the southernmost in Japan, as it was the policy of the Shimazu clan not to construct such structures, even at Kagoshima Castle.

In the secondary area, the daimyō residence was partially reconstructed in 1993, based on the results of archaeological excavations.