According to a number of accounts, the earliest fortifications on the site of present-day Okayama Castle appeared as early as the 14th century and were built by the Nawa clan. The Asahigawa River was used as a natural defensive barrier, protecting one side of the fortifications.
In the early 16th century, the Kanamitsu clan constructed a new castle here, which at the time was known as Ishiyama. In 1573, it came under the control of the Ukita clan, after which Ukita Naoie (1529–1582) launched large-scale reconstruction efforts. He did not live to see the work completed, and construction was continued by his son Hideie.
Hashiba, later known as Toyotomi Hideyoshi, received Odani Castle and the surrounding lands from Oda Nobunaga after the defeat of the Azai clan. However, Odani Castle was located high in the mountains, which made it poorly suited for the effective administration of the territory. For this reason, in 1575 Hideyoshi began constructing a new castle in the village of Imahama on the shore of Lake Biwa. Taking the character naga from Nobunaga’s name, he renamed both the village and the new castle Nagahama.
Kokura Castle is traditionally considered to have been founded by Hosokawa Tadaoki (1563–1645), although by the time the Hosokawa clan came to control these lands, the fortification had already existed since at least 1569 and was most likely built by members of the Mori clan.
In 1334, Ikeda Noriyoshi built a small fort on this site, which over time was repeatedly expanded and rebuilt. During the Ōnin War of 1467–1477, the Ikeda clan supported the Western Coalition. As a result, Ikeda Castle was attacked and captured by the forces of the Eastern Coalition, but it was soon recaptured, allowing it to avoid serious destruction.
Aizu-Wakamatsu is the most powerful and at the same time the oldest castle in the Tōhoku region in the north of Honshu Island. Its history begins in the 14th century and is closely connected with the Ashina clan, whose members claimed descent from the legendary Taira family.
Maruoka Castle is located in the central part of the former city of Maruoka, which is now part of the city of Sakai. This area lies in the northeastern part of Fukui Prefecture. The castle was built on the bank of the Kuzuryu River, on the side opposite Fukui City, which once served as the administrative center of the former Echizen Province. Thanks to its location, Maruoka held significant strategic importance, as it controlled two major routes at once: the Hokurikudo highway leading from Kaga Province and the Mino Kaido road connecting these lands with Mino Province.
