[2] Kōriyama Castle is located at the center of the Nara Basin on the southern end of the Saikyo Hills, on a peninsula protected by the Akishino and Tomio Rivers.

The site appears to have been a physic garden in the Nara period, and the first record of a fortification dates from the late 10th century.

During the Sengoku period, it was extensively remodeled by Tsutsui Junkei (1549-1584), a local petty warlord who had previously been a general commanding the sōhei (armed monks) of Kofuku-ji.

Following the assassination of Nobunaga in 1582, Tsutsui remained neutral in Toyotomi Hideyoshi's battle against Akechi Mitsuhide, and was awarded with confirmation in his existing territory.

However, after Tsutsui Junkei's death, his successor was transferred to Iga Province in 1585 and Kōriyama was awarded to Hideyoshi's younger brother, Toyotomi Hidenaga.

[3] The basic layout was like a whirlpool, with secondary and outer enclosures surrounding the central bailey, which had a tenshu constructed in its northwest corner and the main gate at the southeast edge.

The outer enclosure areas became schools, and a shinto shrine to the Yanagisawa clan was erected in the central bailey.