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Kanagawa · Odawara

Ishigakiyama Castle

石垣山城

Odawara, Kanagawa

CastleMountain castle (yamajiro)Next 100 Fine Castles No. 123

What makes this castle distinctive

The castle said to have appeared overnight actually took about 80 days to build in solid stone, and from its main enclosure you look straight down on Odawara Castle, the fortress it was built to besiege.

Why?

In 1590 Toyotomi Hideyoshi built this castle on a mountain about 3 km from Odawara Castle to besiege the Hojo clan inside. Legend says he built it hidden behind trees and then cut them all down in one night, so the stunned defenders of Odawara lost heart. In fact, Odawara City says, some 40,000 workers spent about 80 days on it, from April to June.^[1][2][3]

Three things not to miss

The Well Enclosure, a valley walled in stone

Where: The Well Enclosure (Ido Kuruwa), in the valley north of the main and second enclosures, reached by steps leading down.
What to look at: The stone walls ringing the valley like a dam, and the well at the bottom.
Why it's interesting: Stone walls were built all around the valley to protect a spring at its bottom, an unusual design the national historic site description calls rare. The walls here are the best preserved in the castle and show the stone-building skills of the time. The well at the bottom is known as Lady Yodo's Make-up Well.^[4][3]
Can you see it?: Visible from outsideFreely accessible within the park. There are steps and level changes, and it is not wheelchair accessible.

Odawara Castle's keep and the city below, seen from Ishigakiyama (June 2010). From here Hideyoshi looked down on the Hojo clan's castle.

Looking down on Odawara Castle from the main enclosure

Where: The lookout platform in the main enclosure (Honjo Kuruwa), at the summit about 240 m above sea level.
What to look at: Odawara Castle's keep about 3 km away, the town around it, and Sagami Bay.
Why it's interesting: Hideyoshi kept up the siege while looking down on the Hojo castle from here. Odawara Castle is about 3 km away as the crow flies. On clear days, the tourism association says, you can even see Tokyo Skytree.^[3][5][4]
Can you see it?: Visible from outsideThe lookout was improved in fiscal 2023.

Kanto's first all-stone castle, in nozura-zumi style

Where: The stone walls around the South Enclosure, the Umaya Kuruwa (second enclosure) and the main enclosure.
What to look at: Wall faces built from natural stones that were barely shaped.
Why it's interesting: It is considered the first castle in the Kanto region walled entirely in stone, and the stonework is said to be by the Anoshu, stonemasons from Omi (today's Shiga Prefecture), in the nozura-zumi (natural-stone) style. Odawara City says that of all the castles Hideyoshi built, only Hizen Nagoya Castle in Saga Prefecture and Ishigakiyama still show original nozura-zumi walls across the whole site.^[1][3][6]
Can you see it?: Visible from outsideSome walls are unstable, so stay outside the fences.

At a glance for visitors

Nearest station: 50 min walk from JR Hayakawa Station
Climb: Steep climb
Time neededEditors' estimate: About an hour to walk around the park.
Access: Open to visitors
Freely open as the Ishigakiyama Ichiya-jo History Park (no admission fee; no on-site office). The Continued Japan 100 Castles stamp is in front of the toilets at the Ichiya-jo car park.

Checked: 2026-10-03

View on map Open in Google Maps Odawara City: Ishigakiyama Ichiya-jo (Japanese)Odawara Tourism Association: Ishigakiyama Ichiya-jo (Japanese)

The story of this castle

Historical record

A mountain overlooking Odawara

The mountain was originally called Kasagakeyama. Lying about 3 km southwest of Odawara Castle across the Hayakawa River, with a sweeping view of the town, it was ideal as a base for a siege. After an all-stone castle was built here, it came to be called Ishigakiyama, "stone wall mountain."^[1][2]

Historical record

Hideyoshi's headquarters for the siege

In 1590 Toyotomi Hideyoshi surrounded the Hojo clan in Odawara with a huge army and built this castle as his headquarters. According to the national historic site description, work began on April 5 and finished on June 26 (dates in the old lunar calendar). The Hojo surrendered on July 5, ending their rule as a Warring States power.^[2][3]

Tradition

The overnight-castle legend and the real construction

It is called the "one-night castle" because, according to legend, Hideyoshi had wall and turret frames built inside the summit woods, covered them with white paper to look like plastered walls, and then had the surrounding trees felled in a single night, so the soldiers in Odawara Castle were shocked and lost their will to fight. In reality, about 40,000 workers spent some 80 days building it.^[1][3]

Scholarly interpretation

A real castle, with tea ceremonies mid-siege

Odawara City says Hideyoshi summoned his consort Lady Yodo, the tea master Sen no Rikyu and Noh performers to hold tea gatherings here, and also received an envoy from the emperor. Large numbers of roof tiles found around the keep base suggest that a keep (tenshu) and turrets stood here. Some tiles are inscribed with the year 1591, so work seems to have continued for a short time after the battle.^[1][4]

Historical record

Left unused, and so preserved

After the battle the castle fell out of use, and there are no signs it was ever altered. Some walls collapsed in the 1923 Great Kanto Earthquake and other quakes, but the layout of the main, second, south and well enclosures survives well. Because its period of use is so clearly limited, it serves as a benchmark site for the history of castle building.^[2][4]

Historical record

National historic site and history park

In 1959 the site was designated the national historic site "Ishigakiyama," and today it is the Ishigakiyama Ichiya-jo History Park, open to walk freely. Odawara City has worked to stabilize loose and collapsing walls, clear trees and add information boards. In fiscal 2023 it upgraded the observation deck and lookout and launched an augmented-reality (AR) feature that recreates the siege on your smartphone.^[2][6][7][5]

People of this castle

Built the castle as his headquarters for the siege of Odawara

Toyotomi Hideyoshi

豊臣秀吉

1537–1598

The warlord who carried on Oda Nobunaga's work and unified Japan. In 1583 he began building Osaka Castle on the site of the Osaka Hongan-ji temple.

Lord

Toyotomi clan

豊臣氏

Timeline

1590
Toyotomi Hideyoshi starts building in April and finishes in June (about 80 days)^[2][1]
1590
In July the Hojo surrender; the castle is later abandoned^[3][2]
1591
Tiles dated 1591 suggest building work continued after the battle^[4]
1923
The Great Kanto Earthquake topples parts of the stone walls^[2]
1959
Designated the national historic site "Ishigakiyama"^[2][1]
2017
Selected as one of the Continued Japan 100 Castles^[1]
2023
Observation deck and lookout upgraded; AR content launched^[5]

Buildings and remains

The keep today

Keep lost

The keep base remains. Many tiles found there lead the city to say a keep and turrets seem to have existed. No building survives or has been rebuilt.

The site today

Maintained as the Ishigakiyama Ichiya-jo History Park (about 5.8 ha), free to visit. There is no management office on site. A private restaurant and patisserie stands in front of the park.

Main buildings

Lost

Keep and turrets

Thought to have existed, based on excavated tiles.^[4]

Key facts

Type: Castle
Setting: Mountain castle (yamajiro)built on a mountain; expect a climbEditorial article
Period: Early modern (1570s–1871)Editorial article
Keep (tenshu): Keep lostthe castle had a keep, but it no longer stands (its stone base may remain)Editorial article
Built by: Toyotomi HideyoshiJapan Castle Foundation
Built: 1590Japan Castle Foundation
Main lords: Toyotomi clanJapan Castle Foundation
Abandoned: 1590Wikipedia (ja)
Remains to see: Stone walls, Baileys / enclosures (kuruwa), Trench cuts (horikiri), Wells, Keep base (tenshudai), Fortified gateways (koguchi)Editorial article
Designation: National Historic Site (Ishigakiyama) (1959)Editorial article
Selection: Next 100 Fine Castles No. 123Japan Castle Foundation

Visiting

Access

Open to visitors

Freely open as the Ishigakiyama Ichiya-jo History Park (no admission fee; no on-site office). The Continued Japan 100 Castles stamp is in front of the toilets at the Ichiya-jo car park.

Address

1383-12 Hayakawa, Odawara, Kanagawa^[1]

Checked: 2026-10-03

Nearest stations and how to get there

JR Hayakawa StationJR Tokaido Line

about 50 min walk · Steep climb

About 50 minutes on foot via the Ishigakiyama farm road, climbing to about 240 m. A taxi takes about 10 minutes, but none wait at the station.^[1][3]

Checked: 2026-10-03

Iriuda Station (Hakone Tozan Railway)Hakone Tozan Railway

about 60 min walk · Steep climb

About 60 minutes uphill, passing the Kanagawa Prefectural Museum of Natural History.^[1][3]

Checked: 2026-10-03

By car / parking

Ichiya-jo car park: 58 spaces, free. Note that you cannot turn right at the Hayakawa intersection on Route 135 when coming from Odawara; large vehicles should use the Chikyu Hakubutsukan-mae intersection on Route 1. There is no regular bus service; a sightseeing loop bus runs only on weekends in tourist seasons.^[1][3]

Checked: 2026-10-03

Grounds opening hours

No official hours are given (the tourism association lists hours and closing days as "–").^[3]Checked: 2026-10-03

Time neededEditors' estimate

About an hour to walk around the park.

Steps, slopes and footing

A hilltop park with steps and level changes throughout; the Well Enclosure is reached by steps going down.^[3][5]

Wheelchairs and strollers

The tourism association says the park has steps and cannot be used by wheelchair.^[3]Checked: 2026-10-03

Toilets and rest

Toilets at the Ichiya-jo car park.^[3]

English signs / audio guide

No official English information could be confirmed.

Seasons

The Odawara tourism association promotes a walking route from Iriuda Station via Chokozan Shotai-ji, famous for its weeping cherry, to Ishigakiyama.^[3]

Photography

Not confirmed

Works, closures and restrictions

Stone-wall conservation work is ongoing; keep away from collapsed sections.^[6]Checked: 2026-10-03

Suggested routes

Taiko Ichiya-jo and Chokozan historic trail 130 min

Start at Iriuda Station on the Hakone Tozan Railway
Chokozan Shotai-ji Temple (weeping cherry)
Pass the Kanagawa Prefectural Museum of Natural History
Climb past information boards on eight warlords who camped at Ishigakiyama
Ishigakiyama Ichiya-jo
Descend to JR Hayakawa Station

Route promoted by the Odawara Tourism Association: 7.5 km, about 2 hours 10 minutes, 238.3 m of elevation change, mostly on paved roads.

Around the castle

Castle town

Chokozan Shotai-ji Temple

A temple known for its weeping cherry tree, on the walking route from Iriuda Station to Ishigakiyama.^[3]

Checked: 2026-10-03

Museum

Kanagawa Prefectural Museum of Natural History

Prefectural natural history museum near Iriuda Station, on the walking route to Ishigakiyama.^[3]

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 who wants to see the 1590 siege of Odawara from both sides along with Odawara Castle, those who appreciate stone-walled castles without a keep, and people who enjoy a hike.

What makes it interesting

Start by looking down on Odawara Castle from the main enclosure to take the attackers' view. Then descend to the Well Enclosure, where the scale of the walls around the valley makes it clear this was no overnight trick but a serious castle.

Before you go

The "one-night castle" is a legend; it actually took about 80 days to build. From the stations it is a steep 50–60 minute climb. There is no regular bus, so come by car or taxi, or use the weekend sightseeing bus in tourist seasons. No buildings survive.

Ways to enjoy it

Install the Odawara Sanpo walking app, and at signboards near the Well Enclosure steps and in the main enclosure you can watch an AR animation of the siege and a 3D model of the whole castle. Visiting Odawara Castle first helps you sense how close the two castles were.

Photos

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Open questions

The stories of a castle appearing overnight and paper made to look like white walls are legends. Odawara City says the castle actually took about 40,000 workers and some 80 days.
The existence of a keep is inferred from excavated tiles; what it looked like is unknown.
That the Anoshu built the walls, and the name "Lady Yodo's Make-up Well," are traditional attributions.
The start and completion dates (April 5 and June 26) are lunar-calendar dates from the Cultural Heritage Online description. Photo rules and English information could not be confirmed.