CastleFlatland castle (hirajiro)Next 100 Fine Castles No. 171
What makes this castle distinctive
This castle was protected by marshes, so Hideyoshi built a dam, diverted a river and turned its surroundings into a lake.
Why?
Bitchu Takamatsu Castle sat on a slight rise in low, flat land surrounded by marshes and wetlands, which made it hard to attack. In 1582 Hashiba (later Toyotomi) Hideyoshi built a dam south of the castle and diverted the Ashimori River to cut it off. With the rainy season adding to the water, the land around the castle was flooded. Part of the dam still survives at Kawazugahana.[1][4]
Takamatsu Castle Ruins Park (the main and second enclosures)
What to look at
The main enclosure site, only slightly higher than its surroundings, the park's ponds and wetlands, and the grave mound of Shimizu Muneharu's head in the main enclosure
Why it's interesting
The main enclosure stands only about 7.7 m above sea level, and the land around it is 1–2 m lower, once marsh and wetland. Place names such as Higashi-numa ("east marsh") and O-numa ("great marsh") survive nearby. With no stone walls or high hill, this was a castle defended by water and mud, and the flat landscape shows it.[1][3]
Can you see it?
Visible from outsideThe park is open to walk. Irises and the "Muneharu lotus" bloom in summer.
The Water Siege Historic Park at Kawazugahana, about 900 m southwest of the castle site
What to look at
A surviving section of the dam, a display of its excavated base, and the arc of the dam's line still traceable in the rice fields
Why it's interesting
A 1998 survey suggests the dam was about 26.5 m wide and around 5 m high, built with straw bags filled with earth on the north side and with earth heaped on woven mats on the south. The Edo-period chronicle Taikoki says it was built in 12 days, but views on what it really looked like differ.[1]
Can you see it?
Visible from outsideOpen to visit as a historic park.
Old maps and materials on the water siege, plus volunteer guides
Why it's interesting
Since no castle buildings survive, stopping here first to see where the dam ran and how the water spread makes the park and Kawazugahana much easier to read. It reopened in a new building in June 2023.[1][2][3]
Can you see it?
Visible from outsideOpen 10:00–15:00; closed Mondays (open on holidays). Free.
At a glance for visitors
Nearest station
10 min walk from JR Bitchu-Takamatsu Station
Climb
No climb
Time neededEditors' estimate
About an hour for the park and museum; add about another hour to walk to Kawazugahana.
Admission
Free
Hours
10:00–15:00
Access
Open to visitors
Takamatsu Castle Ruins Park and the Kawazugahana historic park are open to visit. The stamp is at the museum; on days the museum is closed it is kept at nearby Seikyoan (511-1 Takamatsu, Kita-ku).
The castle stood on the plain on the left bank of the Ashimori River, close to the border between Bizen and Bitchu provinces. The Mori clan built a defensive line of seven castles (the "Sakaime Seven Castles") along the lower Ashimori, and Takamatsu was one of them, facing the Ukita clan to the east and the Oda forces behind them.[1]
02
Historical record
Lord Shimizu Muneharu
The Japan Castle Association lists the Ishikawa family as the builders and the Shimizu family as lords. In March 1582, Hideyoshi sent envoys offering Lord Shimizu Muneharu the two provinces of Bitchu and Bingo if he switched sides, but Muneharu refused and stayed loyal to the Mori.[1][5]
03
Historical record
The water siege of 1582
Hideyoshi surrounded the castle but, to avoid losing men in a direct assault, built a dam to its south and diverted the Ashimori River. With the rainy season, the area around the castle flooded and it was cut off. When Oda Nobunaga was killed in the Honnoji Incident on June 2, Hideyoshi hurried to make peace with the Mori. Muneharu took his own life on June 4 and the castle was handed over; two days later Hideyoshi marched his army back east at speed to fight Akechi Mitsuhide, a move known as the "Great Return from Chugoku."[1]
04
Historical record
Castle and dam turned to farmland
Most of the castle and dam later became fields and houses. The main and second enclosures survive as Takamatsu Castle Ruins Park, and parts of the dam remain at Kawazugahana and at Fukusaki, just south of Ashimori Station (the secondary dam). Nearby are the mounds for Muneharu's head and body and the place where he is said to have died.[1][6]
05
Historical record
National Historic Site
The castle site and the siege dam were made a National Historic Site in 1929 as "Takamatsu Castle ruins, with the water-siege embankment site." Excavations in 1975 and 1997 uncovered parts of the enclosures and moats, stones laid to stop the slopes from collapsing, and ceramics and wooden tableware. In 2017 it was named No. 171 on the Continued Top 100 Japanese Castles list.[1][4][5][6]
The Japan Castle Association lists no keep. An earthen platform is thought to have stood in the main enclosure, but what buildings stood there could not be confirmed.
The site today
The main and second enclosures form Takamatsu Castle Ruins Park, which has a museum. The third enclosure and retainers' quarters are now houses and fields. The siege dam survives as a historic park at Kawazugahana, about 900 m southwest.
Main buildings
Site onlyNational Historic Site
Siege embankment (Kawazugahana)
Part of the dam survives in a historic park.[1][4]
Key facts
Type
Castle
Setting
Flatland castle (hirajiro)built on flat ground, defended by moatsEditorial article
Period
Medieval (c.1185–1570s)Editorial article
Keep (tenshu)
Not yet confirmedwhether a keep existed is still being checkedEditorial article
Built by
Ishikawa clanJapan Castle Foundation
Main lords
Ishikawa clanJapan Castle Foundation
Remains to see
Stone walls, Baileys / enclosures (kuruwa), MoatsEditorial article
Designation
National Historic Site (Takamatsu Castle ruins, with water-siege embankment site) (1929)Editorial article
Selection
Next 100 Fine Castles No. 171Japan Castle Foundation
Visiting
Access
Open to visitors
Takamatsu Castle Ruins Park and the Kawazugahana historic park are open to visit. The stamp is at the museum; on days the museum is closed it is kept at nearby Seikyoan (511-1 Takamatsu, Kita-ku).
Address
558-2 Takamatsu, Kita-ku, Okayama (park and museum)[2][3]
Checked: 2026-10-04
Nearest stations and how to get there
JR Bitchu-Takamatsu StationJR Kibi Line (Momotaro Line)
about 10 min walk · No climb
About 10 minutes on foot from the station to the park. The Kawazugahana embankment site is also about 10 minutes from the station. The secondary dam site on the Ashimori River is right by the next station, Ashimori.[1][3]
About 10 minutes from Okayama-Soja IC on the Okayama Expressway. Parking for about 30 cars (3–5 buses; buses should call the museum in advance).[1][3]
Checked: 2026-10-04
Grounds opening hours
Not confirmedChecked: 2026-10-04
Time neededEditors' estimate
About an hour for the park and museum; add about another hour to walk to Kawazugahana.
Steps, slopes and footing
A flatland castle with almost no slopes or stairs.[1]
Wheelchairs and strollers
Not confirmed.Checked: 2026-10-04
Toilets and rest
Not confirmed.
English signs / audio guide
English signage could not be confirmed.
Seasons
Irises and the "Muneharu lotus" bloom in summer.[3]
Photography
Not confirmed.
Works, closures and restrictions
From August 29 to October 4, the museum stays open 9:00–17:00 on weekends and holidays.[3]Checked: 2026-10-04
Editors' guide
An editorial guide based on sources and confirmed information — not a first-hand visit report.
Who will enjoy it
For fans of famous Sengoku-era episodes, those who want to see where Hideyoshi's "Great Return" began, and anyone who enjoys reading a castle from the lay of the land rather than from walls and keeps.
What makes it interesting
In the park, notice how the main enclosure is just a little higher than its surroundings. Then go to Kawazugahana and look back toward the castle from the dam to imagine this whole plain under water.
Before you go
There is no keep or stone wall: just an open park and historic spots among fields. The museum closes at 15:00 and on Mondays, so plan your timing.
Ways to enjoy it
See the siege maps at the museum first, then walk the park and Kawazugahana. Volunteer guides are available at the museum.
Photos
Visitor reviews
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Open questions
Who built the castle and when is unclear; the Japan Castle Association says "possibly the late 16th century" and names the Ishikawa family.
The Taikoki's figures for the dam (about 21 m wide, 7 m high, 3 km long, built in 12 days) do not match the excavation estimates (about 26.5 m wide, around 5 m high). Views on the dam's real form differ.
Okayama City's tourism site credits the water-siege idea to Hideyoshi's strategist Kuroda Kanbei; here it is described as Hideyoshi's operation, as the official prefectural account does.
Park hours, toilets, accessibility and English signage could not be confirmed.
ReggaemanCC BY-SA 3.0Wikimedia Commons
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