Nirayama Castle: A Japanese Hirayama Fortress in Japan
Site at a Glance
- Rating
- 4
- Popularity
- Low
- Country
- Japan
- Primary era
- Early Modern
- External website
- Open
- Eras represented
- Medieval, Early Modern
- Civilizations
- Ashikaga shogunate, Later Hōjō
- Site type
- Military
- Remains
- Castle
On this page12 sections
History
Nirayama Castle was a Japanese hirayama castle in Japan, built on a low hill and used from the late Muromachi period, the era of the Ashikaga shogunate, through the Azuchi–Momoyama period of political reunification under Oda Nobunaga and Toyotomi Hideyoshi. Also known as Ryūjō, it became a major Hojo stronghold in Izu and is now preserved as a National Historic Site.
Origins and Hojo expansion
The castle’s foundation date remains uncertain. The Hojo Godaiki attributes its first fortification to Toyama Buzen-no-kami, a retainer of Ashikaga Masatomo, the first Horikoshi kubo. A kubo was a high-ranking regional military governor or member of the Ashikaga ruling family, while the Horikoshi kubo exercised Ashikaga authority in Izu. This first construction is placed in the Bunmei era, from 1469 to 1486. Another interpretation places the castle’s completion around 1500, when Kumano Shrine within the castle was enshrined.
The initially modest fortification was seized in 1491 by Ise Moritoki after he defeated Ashikaga Chachamaru, the second Horikoshi kubo. Moritoki, better known as Hojo Soun, then undertook full-scale construction. From Nirayama he controlled Izu and expanded into Sagami. Although he later moved his political seat to Odawara Castle, he continued to live at Nirayama and died there in 1519.
Hojo rule and military campaigns
After the later Hojo clan secured control over the wider Kanto region, Nirayama remained an important base for governing the Izu Peninsula. By the late sixteenth century, Hojo Ujinori, the fourth son of Hojo Ujiyasu, was the castle’s lord and administered Izu from there.
In August 1570, Nirayama was attacked during Takeda Shingen’s invasion of Suruga Province. Hojo Ujinori successfully defended the castle. Twenty years later, Toyotomi Hideyoshi’s campaign against the Hojo brought a much larger assault. Oda Nobukatsu led the attacking army, with Hosokawa Tadaoki, Fukushima Masanori, and Gamo Ujisato also taking part. Ujinori commanded approximately 3,600 defenders and held Nirayama for about 100 days despite being greatly outnumbered.
After other Hojo castles had fallen and the danger to Odawara increased, Tokugawa Ieyasu, acting for Hideyoshi, negotiated with Ujinori. Nirayama eventually surrendered to Ieyasu’s forces. It then became the residence of Ieyasu’s vassal Naito Nobunari, who was transferred in 1601. The castle was abandoned after his departure.
Later ownership and archaeological protection
Most of the former castle grounds later became property of the Egawa family. The family descended from the Egawa Tarozaemon line, whose members served as Nirayama magistrates under the Tokugawa shogunate.
Archaeological investigations have examined 34 locations across the ruins. Excavations carried out from 1990 to 1991 during the rebuilding of Nirayama High School focused on the school grounds, formerly known by the place-name Gozashiki. The ruins are protected under the designation “Nirayama Castle Ruins, including the Attached Fort Ruins.” In 2005, alumni of Nirayama High School founded an organization devoted to restoring the castle.
Remains
Nirayama Castle and its attached fortifications extend across Nirayama, Totedawada, Kanaya, and Nanjo in Izunokuni. The remains occupy the western slope of the Taga–Usami volcanic group, on Tengadake and the ridges that project from it. The main castle follows the small hill of Ryujoyama, at the end of a northwestern ridge from Tengadake, with its principal enclosures arranged in a line from north to south. A map from 1793 names these enclosures, in order from north to south, as the Third Enclosure, Gongen Enclosure, Second Enclosure, and Main Enclosure.
Main castle and attached fortifications
Supporting fortifications stood on four nearby hills, and the wider complex was described as having Western-style fortifications. Its surviving and excavated defenses include water moats, dry moats, earthen ramparts, enclosed areas, entrances, and traces of residential compounds. Earthen walls and enclosure lines remain visible, while paths now pass through the ruins.
Second Enclosure
A trench in the Second Enclosure produced a line of foundation stones. These stones confirm that a building once stood there, adding physical evidence to the enclosure’s former built environment.
Tengadake–Totedawada fortifications
In the Tengadake–Totedawada group, moats were arranged in an L-shaped configuration. Sections of bedrock were left unexcavated to form enclosed areas, and one moat reached a depth of 2.5 meters. Large moats were also identified at the Oyashiki No. 1, Sotouchi No. 1, and Momejima No. 4 locations.
Residential and service areas
Houchi No. 1
Houchi No. 1 contains post-built structures, rows of postholes, a well-like feature, and ditches. Unglazed serving vessels and other ceramics were recovered there. The area is interpreted as a residential compound enclosed by ditches.
Houchi No. 5
At Houchi No. 5, excavation revealed a covered drainage channel, a stone-paved road-like feature more than 5 meters wide, and a moat. Unglazed vessels, chopsticks, trays, and other serving implements came from the fill of the drainage channel.
The north–south moat at Houchi No. 5 was a shoji moat, a defensive ditch divided by earthen or unexcavated barriers. A barrier-like division lay at its base, with fascine work, bundles of material used to reinforce earthworks, on its slope. The moat is thought to have continued into those identified at Oyashiki No. 1 and Oyashiki No. 3.
Gozashiki
The area occupied by Nirayama High School was formerly associated with Gozashiki. Excavation there uncovered a well, a garden pond, and remains believed to represent a residential compound. The positions of the castle’s samurai residences and government offices remain unknown, but these finds demonstrate the presence of organized domestic space within the former castle grounds.
Nearby sites
