CastleMountain castle (yamajiro)Japan's 100 Fine Castles No. 44
What makes this castle distinctive
Moats shaped from earth alone, without a single stone, form a grid pattern with Mount Fuji behind them on clear days.
Why?
Yamanaka Castle was built by the Hojo clan of Odawara on a mountain west of Hakone, using no stone walls at all: its defenses were simply dug and piled up from earth. The shoji-bori, a moat whose floor is divided into cells by earthen ridges, is a hallmark of Hojo castles. After excavation the moats and baileys were restored, and the city notes that on clear days you can see Mount Fuji beyond them.[1][2]
The shoji-bori moats at the West Bailey and West Turret
Where
The west side of the castle, around the West Bailey (Nishinomaru) and the West Turret (Nishi Yagura).
What to look at
The grid of earthen ridges left on the moat floor, and the moats running in several parallel rows.
Why it's interesting
Leaving ridges of earth inside the moat to divide it into cells makes it look, from above, like the wooden frame of a shoji paper door, hence the name shoji-bori. The city puts the multi-row shoji-bori at the West Turret and West Bailey first on its list of highlights. Today the earth is covered with grass, but originally it was bare red clay, slippery and hard to climb.[1][2]
Can you see it?
Visible from outsideVisible from the walking paths. Do not step into the moats or onto the slopes.
Daisaki Demaru, the long outwork stretching south of the main castle.
What to look at
Earthen ridges lined up like the rungs of a ladder along the floor of a long moat.
Why it's interesting
As war with Toyotomi Hideyoshi approached, Yamanaka became a frontline base, and outworks like this one were added in a major rebuild. From Daisaki Demaru you can look out over northern Izu and the Sunto area, and the city lists its moat among the highlights. Collapsed slopes and ridges here were repaired in 2017–2018.[1][2][5]
Can you see it?
Visible from outsideVisible from the walking paths.
03
The winding approach to the Second Bailey gate
Where
The path leading up to the entrance (koguchi) of the Second Bailey.
What to look at
A sloping path that bends again and again so no one can go straight in.
Why it's interesting
This is another of the city's listed highlights. Bending the approach meant attackers could not rush the gate head-on. Excavations also found traces of wooden bridges over the moats and of gateposts.[1][2]
Can you see it?
Visible from outsideYou can walk it as part of the paths.
At a glance for visitors
Nearest station
from JR Mishima Station (by bus)
Climb
Steep climb
Time neededEditors' estimate
About 1.5–2 hours to see the main baileys and the Daisaki outwork.
Admission
Castle and warlord commemorative seals cost 300 yen each (when the shop is closed, you can order through the post box at the entrance)
The historic park is free and has no set opening hours, but the city asks visitors not to enter at night because there is no lighting and wild animals may appear. Stay out of the moats and off the slopes. Drones are banned without permission. The Japan 100 Castles stamp is at the entrance of the shop and can be used even when the shop is closed.
Yamanaka Castle stands at 580 m on the mountains west of Hakone, ringed by steep slopes between the sources of two rivers. Northern Izu bordered the lands of the Takeda and Imagawa clans, so this was the key point for defending the Hojo clan's main castle at Odawara from the west. The castle covered an area 500 m east to west and 1,000 m north to south.[1]
02
Historical record
A Hojo fort without a resident lord
Yamanaka was built in the later Sengoku (Warring States) period by the Hojo clan of Odawara. It was a bancho, a fort with rotating garrisons rather than a resident lord. The city dates its construction to around 1530–1560, while the Japan Castle Foundation gives around 1558–1570.[1][7]
03
Tradition
Fallen in half a day
When Toyotomi Hideyoshi launched his campaign against Odawara, Yamanaka became a frontline base along with Nirayama and Ashigara castles, and its moats and outworks were heavily rebuilt. On March 29, 1590, an army of 67,000 attacked. The 4,000 Hojo defenders fought desperately, but against firearms and overwhelming numbers the castle is said to have fallen in only half a day. It was abandoned afterward.[1][3]
04
Tradition
A temple where both sides lie together
At Sokanji Temple, on the site of the Third Bailey, the graves of the castle commander Matsuda Yasunaga and of warriors from both sides stand together. The temple is said to have been founded by the daughter of Mamiya Yasutoshi, a Hojo commander killed in the battle, to pray for her father. The castle itself lay buried under soil for nearly 400 years.[1][8]
05
Historical record
An earthen castle brought back by excavation
The site became a National Historic Site in 1934, and Mishima City began excavating it in 1973. Digs revealed moats, earthen ramparts, and traces of wooden bridges and gateposts, and over more than 20 years the moats and baileys were restored. The site opened as a historic park in 1981. A 2019 typhoon and heavy rain in 2021 caused moat slopes to collapse, and the city is continuing repairs with the aim of finishing in fiscal 2026.[1][3][4]
Typhoon Hagibis damages moat slopes; repair work begins[4]
Buildings and remains
The keep today
No keep was built
An earthen Sengoku-period mountain fort that never had a keep.
The site today
A historic park where the moats, earthen ramparts and baileys were restored after excavation. There are no buildings; the earthworks are protected by a layer of soil and grass to prevent erosion. The site lies along National Route 1.
Main buildings
Site only
Castle buildings (turrets, gates, bridges)
No buildings survive. Excavation found traces of wooden bridges and gateposts.[1]
Key facts
Type
Castle
Setting
Mountain castle (yamajiro)built on a mountain; expect a climbEditorial article
Period
Medieval (c.1185–1570s)Editorial article
Keep (tenshu)
No keep was builtthe castle never had a keepEditorial article
Built by
Later Hōjō clan, Hōjō UjiyasuJapan Castle Foundation
Built
1558Japan Castle Foundation
Main lords
Later Hōjō clan, Matsuda clanJapan Castle Foundation
National Historic Site (Yamanaka Castle ruins) (1934)Editorial article
Selection
Japan's 100 Fine Castles No. 44Japan Castle Foundation
Visiting
Access
Open to visitors
The historic park is free and has no set opening hours, but the city asks visitors not to enter at night because there is no lighting and wild animals may appear. Stay out of the moats and off the slopes. Drones are banned without permission. The Japan 100 Castles stamp is at the entrance of the shop and can be used even when the shop is closed.
JR Mishima Station (by bus)JR Tokaido Shinkansen and Tokaido Line, Izuhakone Railway Sunzu Line
Steep climb
Take a Tokai Bus (bound for Motohakone-ko and others) for about 30 minutes to the Yamanakajo-ato stop. The ruins are on a mountainside, and the paths go up and down a lot.[2]
Mondays, the New Year period, and occasional closures for bad weather
Admission
Castle and warlord commemorative seals cost 300 yen each (when the shop is closed, you can order through the post box at the entrance)[2]
Checked: 2026-10-03
By car / parking
About 30 minutes from central Mishima along National Route 1 toward Hakone Pass, or about 15 minutes from the Mishima-Tsukahara IC on the Izu-Jukan Expressway. Two free lots: one opposite the shop (cars only) and a large lot down the slope from the shop (cars and buses). Both are open 9:00–17:00 and locked outside those hours.[2]
Checked: 2026-10-03
Grounds opening hours
No set hours, free (avoid visiting at night)[2]Checked: 2026-10-03
Time neededEditors' estimate
About 1.5–2 hours to see the main baileys and the Daisaki outwork.
Steps, slopes and footing
A hillside site with steep ups and downs and mostly earthen paths. There is no lighting.[1][2]
Wheelchairs and strollers
Not confirmedChecked: 2026-10-03
Toilets and rest
Toilets at the plaza opposite the shop and next to the shop (the toilet at the West Gate entrance is closed due to a leak).[2]
English signs / audio guide
English signage on site is not confirmed.
Seasons
Flowering trees and shrubs bloom from spring to late autumn, and on clear days Mount Fuji can be seen beyond the shoji-bori moats.[1]
Photography
Flying drones without permission is prohibited.[2]
Works, closures and restrictions
Disaster-recovery work is scheduled to continue through fiscal 2026, and paths near the work may be closed temporarily (the city says all paths are currently open). On Sunday, October 25, 2026, from 13:00, the Yamanaka Castle Mini Warrior Parade of people in armor will tour the site (canceled if it rains).[4][6]Checked: 2026-10-03
A temple on the site of the Third Bailey, where the graves of commander Matsuda Yasunaga and warriors from both sides stand together.[1]
Checked: 2026-10-03
Editors' guide
An editorial guide based on sources and confirmed information — not a first-hand visit report.
Who will enjoy it
For anyone who wants to see how an earthen castle worked rather than stone walls and keeps, first-timers to Sengoku-period mountain castles, and lovers of views of Mount Fuji.
What makes it interesting
Start with the shoji-bori at the West Bailey and West Turret; the neat grass grid is easiest to understand from above. Then follow the long moat of the Daisaki outwork. End at Sokanji, where the graves of fighters from both sides recall the weight of the half-day battle of 1590.
Before you go
There are no buildings; the earthworks are the attraction. The site is on a mountainside with steep ups and downs and no lighting, so wear good shoes and go in daylight. The shop is closed on Mondays.
Ways to enjoy it
It is fun to walk while thinking about how those grids in the moats stopped attackers. On a clear day, look for Mount Fuji around the West Turret and the shoji-bori. Bullets and everyday items found in the excavations are on display at the Mishima City Local History Museum.
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Open questions
The city (around 1530–1560) and the Japan Castle Foundation (around 1558–1570) give different dates for its construction.
The city gives 67,000 attackers and 4,000 defenders; a secondary source gives 68,000 and 3,000. The half-day fall is described as tradition.
That Mamiya Yasutoshi's daughter founded Sokanji, and that finds are shown at the Mishima local history museum, come from a secondary source (Wikipedia).
Accessibility, English signage and the walking distance from the bus stop could not be confirmed.
Mocchy at Japanese WikipediaPublic domainWikimedia Commons
