CastleMountain castle (yamajiro)Next 100 Fine Castles No. 117
What makes this castle distinctive
A quarrel over this small hilltop castle gave Toyotomi Hideyoshi his reason to attack Odawara and finish unifying Japan.
Why?
Sanada Masayuki built Nagurumi as his front-line base for taking Numata Castle from the Hojo clan. In 1589, Inomata Kuninori, the Hojo commander at Numata, seized Nagurumi. Hideyoshi used this as his pretext for war on the Hojo, and their defeat at Odawara the following year completed his unification of Japan.[1][3]
The main and second enclosures, still in their original shape
Where
The heart of the castle site; a stone monument stands in the middle of the main enclosure (honkuruwa).
What to look at
The row of enclosures (kuruwa) outlined in lawn, and the ditches and earthen banks between them.
Why it's interesting
Nagurumi has no stone walls or buildings; it was carved out of the earth. The local tourism association notes that the main enclosure, the second enclosure and others keep their original shape, and the 2015 landscaping made the layout easier to read.[2]
Can you see it?
Visible from outsideThe site is open to walk around.
02
Looking toward Numata from the Sasa enclosure
Where
The Sasa-kuruwa, the outermost enclosure at the tip of the castle.
What to look at
The view across the Tone River in the direction of the Numata Castle ruins.
Why it's interesting
Nagurumi was the Sanada clan's forward base for capturing Hojo-held Numata Castle. Looking toward Numata from the Sasa enclosure, you can imagine how close the two sides were as they faced off.[2][1]
Can you see it?
Visible from outsideHow far you can see depends on the weather.
Around the edges of the site, near where the Tone and Akaya rivers meet.
What to look at
The cliffs dropping toward the rivers at the castle's edges, and the defended enclosures on the one landward side.
Why it's interesting
The castle was built on a natural fortress of ground with cliffs on three sides. Only the side without cliffs needed strong defenses, which is thought to have made even this small castle easier to hold.[2]
Can you see it?
Partly visibleYou can see the drop from the top, but stay behind fences and on the paths near the cliff edges.
At a glance for visitors
Nearest station
45 min walk from JR Gokan Station
Climb
Some climbing
Time neededEditors' estimate
Allow 40 minutes to an hour to walk the site and watch the visitor center video, a little longer with a guided tour.
Admission
No admission fee listed (castle seals 300 yen each)
Hours
9:00–16:00
Access
Open to visitors
The castle site is open to visit. At the Nagurumi Castle visitor center you can ask for a free tour by a volunteer history guide.
Nagurumi is a mountain castle (yamajiro) built on high ground near where the Tone and Akaya rivers meet, with cliffs on three sides. Across the river lay Hojo-held Numata Castle, and Nagurumi was the Sanada clan's front line for taking it. The Hojo in turn built Myotokuji Castle on the opposite side of the river to face it.[1][2]
02
Tradition
Sanada Masayuki's forward base
The site is said to have begun as a residence built by the Nagurumi family in the Muromachi period. After Uesugi Kenshin died suddenly in 1578, Sanada Masayuki, then serving the Takeda clan, captured the residence and built Nagurumi Castle as a forward base for taking Numata Castle. The Japan Castle Foundation dates its construction to 1579.[2][8]
03
Historical record
The Nagurumi incident and the road to Odawara
In 1589, Inomata Kuninori, the Hojo commander of Numata Castle, seized Nagurumi. Toyotomi Hideyoshi used this as his reason to attack the Hojo, launching the Odawara campaign in 1590. The Hojo were defeated and Hideyoshi completed the unification of Japan. An incident over one small hilltop castle helped bring the Sengoku (Warring States) period to an end.[1][3]
04
Historical record
No buildings, but the earthworks remain
No stone walls or buildings survive, but enclosures such as the main and second enclosures still keep their original shape. The site was designated a Gunma Prefectural Historic Site in 1949.[1][2]
05
Historical record
A landscaped site with a visitor center
The site was landscaped in 2015 so that the enclosures are easier to make out. The nearby Nagurumi Castle visitor center shows an 8-minute video about the castle, has displays, and sells castle seals (goshuin-style souvenirs). In 2017 Nagurumi was chosen as one of the Next 100 Fine Castles of Japan.[2][4][3]
Gunma Prefectural Historic Site (Nagurumi Castle ruins) (1949)Editorial article
Selection
Next 100 Fine Castles No. 117Japan Castle Foundation
Visiting
Access
Open to visitors
The castle site is open to visit. At the Nagurumi Castle visitor center you can ask for a free tour by a volunteer history guide.
Address
3437 Shimotsu, Minakami, Tone District, Gunma (castle site); visitor center at 3462-2 Shimotsu[1][2]
Checked: 2026-10-03
Nearest stations and how to get there
JR Gokan StationJR Joetsu Line
about 45 min walk · Some climbing
About 45 minutes on foot. Cross at the light in front of the station and walk down the slope, turn left at the four-way junction, go straight and turn right just before the expressway overpass. Join National Route 17, cross the Tone River on the Tsukiyono Bridge and follow the road; there are two guide signs along the way. A taxi takes about 7 minutes.[5][6]
Checked: 2026-10-03
Hours and admission
Nagurumi Castle visitor center
Hours
9:00–16:00
Closed
New Year holidays
Admission
No admission fee listed (castle seals 300 yen each)[2][10][4]
Checked: 2026-10-03
Volunteer history guides (Minakami History Guide Association)
Hours
9:30–15:30 (9:30–14:00 from July 20 to September 30)
Closed
Tuesdays and Thursdays, and in winter (mid-December to mid-March); occasional extra closures
About 5–6 minutes from the Tsukiyono exit of the Kan-Etsu Expressway. Free parking for about 20 cars and 2 buses. From Jomo-Kogen Station on the Joetsu Shinkansen, a taxi takes about 7 minutes.[5][9]
Checked: 2026-10-03
Grounds opening hours
Not confirmedChecked: 2026-10-03
Time neededEditors' estimate
Allow 40 minutes to an hour to walk the site and watch the visitor center video, a little longer with a guided tour.
Steps, slopes and footing
The walk from Gokan Station crosses the Tone River and includes slopes, according to the tourism association's map. Footing and steps within the site could not be confirmed officially.[6]
Wheelchairs and strollers
Not confirmedChecked: 2026-10-03
Toilets and rest
Not confirmed
English signs / audio guide
Not confirmed
Seasons
The local guide association recommends the cherry blossoms in the main enclosure in spring.[11]
Photography
Not confirmed
Works, closures and restrictions
The visitor center's phone line is currently unavailable, so the Minakami Tourism Association asks visitors to call it instead (0278-62-0401, weekdays only).[2]Checked: 2026-10-03
Town-designated castle ruins north of Nagurumi, home of Ogawa Kayusai, who survived the struggles among the Uesugi, Hojo and Sanada. Its dry moats are well preserved.[1]
A National Historic Site from the late to final Jomon period, where dwellings, a ritual area and a water site were found close together. Finds are shown at the Tsukiyono Local History Museum, open Sundays only.[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 stand where the end of the Sengoku period was set in motion. It pairs well with Numata and Iwabitsu, the other Sanada-related castles nearby.
What makes it interesting
The row of enclosures outlined in lawn, and the view from the Sasa enclosure at the tip. Look at how the cliffs on three sides made up for the castle's small size.
Before you go
There are no buildings or stone walls here; it is an earthwork site. Watching the 8-minute video at the visitor center first makes the story much easier to follow. The visitor center's phone is currently out of service, so contact the Minakami Tourism Association with questions.
Ways to enjoy it
Look toward Numata from the Sasa enclosure and imagine the Sanada and Hojo facing off across the river. Ask for a free volunteer guide to point out the features of the terrain.
Photos
Visitor reviews
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Open questions
The Japan Castle Foundation dates the castle to 1579, while the tourism association says Sanada Masayuki took the Nagurumi residence after Uesugi Kenshin's death in 1578. That it began as the Nagurumi family's residence is only said to be so.
The distance from Gokan Station is about 4 km on the tourism association's map but about 2.8 km on the guide association's page; both give about 45 minutes on foot.
Site hours, toilets, accessibility, English information and the Next 100 Castles stamp location could not be confirmed in official sources.
QurrenCC BY-SA 3.0Wikimedia Commons
