CastleHilltop castle (hirayamajiro)Next 100 Fine Castles No. 122
What makes this castle distinctive
Cars on the Daisan Keihin expressway race right past a Warring States castle whose deep dry moats still wind through a bamboo grove.
Why?
Kozukue was a medieval castle defended not by stone walls but by ditches dug into the earth and banks piled up from the soil. When the Daisan Keihin expressway was built in 1963, part of the castle area was discovered, but its west edge was cut away without a proper investigation. Even so, the surviving part keeps its huge dry moats and earthen ramparts in nearly their original shape.[7][1]
Between the East Enclosure (Ninomaru Plaza) and the West Enclosure (Honmaru Plaza), visible from the walking paths.
What to look at
How deep the moats are, and the earthen banks raised on both sides of them, a feature known as a double rampart.
Why it's interesting
The dry moats survive in a great loop from the East Enclosure to the West Enclosure. Raising banks on both sides of a moat is considered a hallmark of castle building by the Hojo clan of Odawara. Excavations by the city found that the face of the north moat had been smoothed and was steep, about 35 degrees near the top and about 49 degrees lower down.[2][7]
Can you see it?
Visible from outsideOpen to walk freely as Kozukue Castle Citizens' Forest. Many parts of the moats are fenced off.
Honmaru Plaza (West Enclosure) and Ninomaru Plaza (East Enclosure).
What to look at
The two broad, flat plazas and the smaller enclosure that links them.
Why it's interesting
Today the West Enclosure is called the honmaru (main enclosure) and the East the ninomaru (second enclosure), but no one knows for sure which was the main one. The East Enclosure is thought to have been the original core, with the Hojo clan greatly enlarging the castle from east to west as they pushed into Musashi Province (today's Tokyo, Saitama and part of Kanagawa).[2]
Can you see it?
Visible from outsideBoth plazas are open to visitors.
03
The turret base that watched over the whole castle
Where
The high ground linking the East and West Enclosures, marked as the turret base (yagura-dai) on the site map.
What to look at
The raised earthen platform and the view it commands.
Why it's interesting
This high point is thought to have held a lookout turret (yagura). Besides overseeing the whole castle, it is described as letting defenders strike from the side at enemies who broke into either enclosure from the south.[2]
Can you see it?
Visible from outsideVisible from the walking path. No structure survives.
At a glance for visitors
Nearest station
15 min walk from JR Kozukue Station
Climb
Some climbing
Time neededEditors' estimate
About 1.5 hours including the walk to and from the station.
Admission
Free (check in at reception first)
Hours
Mon–Sat 9:00–21:00; Sundays and holidays 9:00–17:00
Access
Open to visitors
Open to walk freely as Kozukue Castle Citizens' Forest. There is no parking, so use public transport. The Continued Japan 100 Castles stamp is on the ground floor of the Shirosato Kozukue Community Center near Kozukue Station and is available only during opening hours (per the 2020 guide map). The center's second floor has a small exhibit on Kozukue Castle's history produced by the Yokohama History Museum.
Kozukue Castle stood on a hill jutting out toward the Tsurumi River. It sat where routes from the port of Kanagawa (in today's Kanagawa Ward), the river itself and the Kamakura Kaido road all met, making it the base for controlling what is now northern Yokohama. It is thought to have been built by the mid-15th century, in the Muromachi period, though the exact date is unknown.[1][7]
02
Historical record
Taken by Ota Dokan
Records show that in 1478, during the rebellion of Nagao Kageharu in the Kanto region, Ota Dokan attacked the "Kozukue stronghold" held by warriors on Kageharu's side. The castle is said to have fallen to Dokan at this time.[7][1]
03
Historical record
A key Hojo stronghold
In the Warring States period the castle became an important military base for the Hojo clan of Odawara as they spread across the Kanto region, and it seems to have been rebuilt. Kasahara Nobutame, a senior Hojo retainer, served as castellan (the vassal in charge of the castle), and members of the Hojo family later held it as lords.[1]
04
Historical record
No final battle; moats and ramparts remain
There is no record of fighting at Kozukue during Toyotomi Hideyoshi's 1590 campaign against Odawara. The castle was abandoned after Tokugawa Ieyasu took over the Kanto region. No buildings survive, but the main features, including the big dry moats, earthen ramparts and the main and second enclosures, remain in nearly their original form.[1]
05
Historical record
Cut by a highway, now being studied
Part of the castle area was discovered in 1963 during construction of the Daisan Keihin expressway, but in that era of rapid economic growth it was not properly investigated. In 1977 the site became Kozukue Castle Citizens' Forest, protected as woodland open to the public. Since fiscal 2021 the Yokohama City Board of Education has been excavating the site as a first step toward better ways to protect and use it.[7][8][6]
The castle is thought to have been built by this time[1]
Ota Dokan attacks the "Kozukue stronghold" during Nagao Kageharu's rebellion[7][1]
after Ieyasu's arrival in Kanto
The Hojo clan falls; the castle is later abandoned[1]
Part of the castle is uncovered during construction of the Daisan Keihin expressway[7]
The site becomes Kozukue Castle Citizens' Forest[8]
The Yokohama City Board of Education begins excavations[7][6]
Buildings and remains
The keep today
No keep was built
A medieval castle defended by earthworks; it never had a keep.
The site today
The site is maintained as Yokohama's Kozukue Castle Citizens' Forest (about 4.6 ha), with paths through the bamboo groves. Its west edge was cut away by the Daisan Keihin expressway.
Main buildings
Site only
Turrets (turret base and turret site)
Places said to have held a lookout turret and an armory. No structures survive.[2]
Key facts
Type
Castle
Setting
Hilltop castle (hirayamajiro)built on a low hill rising from the plainEditorial article
Period
Medieval (c.1185–1570s)Editorial article
Keep (tenshu)
No keep was builtthe castle never had a keepEditorial article
Built
1524Japan Castle Foundation
Main lords
Uesugi clan, Later Hōjō clan, Nagao clan, Hōjō clan, Musashi no Kuni no MiyatsukoJapan Castle Foundation
Next 100 Fine Castles No. 122Japan Castle Foundation
Visiting
Access
Open to visitors
Open to walk freely as Kozukue Castle Citizens' Forest. There is no parking, so use public transport. The Continued Japan 100 Castles stamp is on the ground floor of the Shirosato Kozukue Community Center near Kozukue Station and is available only during opening hours (per the 2020 guide map). The center's second floor has a small exhibit on Kozukue Castle's history produced by the Yokohama History Museum.
JR Kozukue StationJR Yokohama Line (local trains only)
about 15 min walk · Some climbing
Head west from the station along the tracks, cross the JR Yokohama Line and reach the forest entrance. Inside, the paths go up and down the hill.[5][1]
Checked: 2026-10-03
Hours and admission
Shirosato Kozukue Community Center (stamp and mini exhibit)
Hours
Mon–Sat 9:00–21:00; Sundays and holidays 9:00–17:00
Closed
Fourth Monday of each month (next day if a holiday); December 28 – January 4
There is no parking at the site; visitors are asked to come by public transport.[1]
Checked: 2026-10-03
Grounds opening hours
Not confirmedChecked: 2026-10-03
Time neededEditors' estimate
About 1.5 hours including the walk to and from the station.
Steps, slopes and footing
A wooded hill with dirt paths, slopes and ups and downs along the moats.[2]
Wheelchairs and strollers
Not confirmedChecked: 2026-10-03
Toilets and rest
Not confirmed
English signs / audio guide
No English information could be confirmed.
Seasons
Each spring the Kozukue Castle Festival brings a samurai procession through town and a send-off ceremony in Honmaru Plaza (held April 12 in 2026; canceled in rain).[4][3]
Photography
Not confirmed
Works, closures and restrictions
The Yokohama City Board of Education continues to excavate the site; parts may be off limits while work is under way (not confirmed).[6][9]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
Good for anyone curious about earthwork castles without stone walls, and for those who want to feel the shape of a Warring States castle right next to the city. It is close to Shin-Yokohama and Nissan Stadium, so it is easy to fit in around other plans.
What makes it interesting
The dry moats are the highlight. Compare the moat floor with the top of the ramparts and you can imagine how exposed attackers were to defenders above. From the air you can also see the Daisan Keihin running right beside the castle, where it sliced off the west edge.
Before you go
This is a castle site in the woods with no buildings or stone walls. Some dirt paths can be slippery, so wear good walking shoes. There is no parking.
Ways to enjoy it
See the diorama in the mini exhibit at the Shirosato Kozukue Community Center first, and the layout of moats and enclosures will make more sense in the woods. With the Kohoku Tourism Association's guide map in hand, walk in order from Negoya, the foot of the hill where the lord's residence stood, up to Honmaru Plaza.
Photos
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Open questions
When the castle was built and by whom is unknown, as is which of the two enclosures was the main one.
The stamp location and community center hours come from the 2020 guide map; check with the center before visiting.
No national, prefectural or city historic-site designation could be confirmed. Forest opening hours, toilets, barrier-free access, photo rules and English information are also unconfirmed.
Saigen JiroCC0Wikimedia Commons
