[1] During the Muromachi and Sengoku period, the area of Kōka was ruled by many autonomous petty lords.

Nakamura chose a location on the 100-meter Mount Daiko in the eastern part of Minakami to be his stronghold.

Following the Siege of Odawara (1590), he was awarded with Sunpu Castle, which had been vacated by Tokugawa Ieyasu, who had been ordered by Hideyoshi to transfer to the Kantō region.

During the Battle of Sekigahara, Natsuka was loyal to the Western Army under Ishida Mitsunari, but was unable to participate in any combat.

After the battle, he returned to Minakuchi Okayama Castle, which came under attack by the forces of Ikeda Nagayoshi and Kamei Korenori.