Rikan Castle is a historic mountain castle located in Hirafuku, Sayo Town, Sayo District, Hyogo Prefecture. Designated a National Historic Site of Japan, the castle stands atop Mount Rikan at an elevation of 373 meters. During the early Edo period (1603–1868), it once featured a towering keep that appeared to float above the surrounding mist. This striking appearance earned it the alternative name Unotsuki Castle, meaning “Castle Piercing the Clouds.”
The ruins lie northeast of Hirafuku, a historic post town that flourished along the Inaba Road, an important route connecting the Harima and Inaba regions. Today, the stone walls and mountain setting offer a glimpse into the strategic importance and architectural ambition of Japan’s former mountain fortresses.
Rikan Castle was built in a connected series of fortified enclosures along the mountain ridge. The main enclosure, or honmaru, occupied the summit. The second enclosure, or ninomaru, lay to the south, with an area known as the Baba farther down the slope. Karasumaru stood to the northeast, while Osakamaru was located to the west. The third enclosure, or sannomaru, occupied a lower area on the western side.
This arrangement of multiple enclosures allowed the defenders to protect the summit and control approaches from different directions. The castle’s elevated position also provided a strategic advantage overlooking the surrounding countryside and the important road below.
Rikan Castle was founded in 1349, during the Nanboku-cho period, by Bessho Atsunori, a member of the Bessho family, which was connected to the powerful Akamatsu clan. The castle served as a northern defensive stronghold for Shirohata Castle, the Akamatsu family’s principal base.
The Bessho family’s fortunes changed during the Kakitsu Disturbance of 1441, when the Akamatsu clan was defeated and the Bessho family also lost its power. In 1466, however, Bessho Harusada, a descendant of the family, recaptured Rikan Castle and restored its position as a local stronghold.
During the turbulent Sengoku period (approximately the mid-15th to late 16th century), the castle became caught up in the struggle for control of western Japan. Hashiba Hideyoshi, a general serving Oda Nobunaga, advanced into the Chugoku region. The castle’s lord at the time, Bessho Sadamichi, initially submitted to the Hashiba forces.
However, when Bessho Nagaharu, the lord of Miki Castle, rebelled against the Oda clan, a castle lord named Hayashi Osamu sided with him. In 1578, Rikan Castle was attacked by Amago Katsuhisa, the lord of nearby Kozuki Castle, and his retainer Yamanaka Yukimori, who were aligned with the Oda forces. Rikan Castle subsequently fell.
Later that year, Kozuki Castle itself was captured by the Mori clan. Rikan Castle then came under the control of Ukita Naoie, who supported the Mori side at the time. The Ukita family subsequently submitted to Hashiba Hideyoshi and retained the castle until the Battle of Sekigahara in 1600, which reshaped Japan’s political landscape.
After the Battle of Sekigahara, Ikeda Terumasa received control of Harima Province. In 1601, he granted the Hirafuku domain, worth 22,000 koku of rice in assessed annual production, to his nephew Ikeda Yoshiyuki.
Yoshiyuki undertook a major reconstruction of Rikan Castle. He built a three-story keep, reinforced the enclosures with stone walls, and connected the fortified areas with covered or enclosed passageways. At the foot of the mountain, he also developed a castle town with a residence for the lord, samurai quarters, and a commercial district along the main road.
The impressive castle, however, raised concerns under the newly established Tokugawa shogunate, which closely monitored the construction and military capabilities of regional lords. Ikeda Terumasa ordered the castle keep to be demolished. In 1609, Yoshiyuki was transferred to serve as castellan of Shimotsui Castle in Bizen Province, and the three-story keep and other major structures at Rikan Castle were dismantled.
In 1615, Ikeda Teruoki, the sixth son of Ikeda Terumasa, received a domain worth 25,000 koku and became lord of the newly established Hirafuku Domain. His rule was short-lived. In 1631, he died without an heir while serving as lord of Ako Domain, and the Hirafuku Domain was abolished. Rikan Castle was abandoned as a result.
The territory subsequently came under the control of the Matsudaira family, a house of hatamoto, or direct retainers of the shogun. An administrative residence known as a jin’ya was established within the post town, continuing local administration without the need for a functioning mountain castle.
Preservation and maintenance work at Rikan Castle began in fiscal year 2015, including repairs to its stone walls and improvements to the historic site. Because sections of the masonry have deteriorated and there is a risk of collapse, entering the castle ruins independently is prohibited.
Visitors may be able to reach the third enclosure as part of an authorized guided tour. Anyone hoping to explore the ruins should check the latest arrangements with the local authorities or tour organizers before visiting, as access restrictions are intended to protect both the historic remains and visitors’ safety.
Archaeological investigations and recovery work following severe flooding in the Sayo area have uncovered traces of the castle’s buildings and defenses. These include foundation stones, post-built structures, and remnants of moats. Roof tiles, ceramics, and other everyday objects have also been discovered, helping researchers reconstruct how the castle was built and how people lived there.
These findings add to the historical value of Rikan Castle, revealing evidence of its development from a medieval mountain stronghold into a more elaborate early Edo-period fortress. Although the main buildings no longer survive, the stonework, remains of the enclosures, and dramatic mountain setting convey the scale and strategic importance of this remarkable historic site.