126.石垣山城~Ishigakiyama Castle

”The castle built in one night” was not built in a day.

石垣山城の入り口の一つ~One of the entrances of Ishigakiyama Castle

立地と歴史~Location and History

Ishigakiyama Castle is nicknamed as “Ichiya-jo” which means a castle built in one night. It comes from an event in Siege of Odawara Castle between Hideyoshi Toyotomi and the Hojo clan in 1590.

小田原城~Odawara Castle

When this castle was completed on a mountain called Kasagakeyama, located in the west of Hojo in Odawara, Hideyoshi ordered his men to cut down all the trees around the castle in one night. Hojo was very surprised to see the castle suddenly appear the next morning. The story calls it Ichiya-jo. However, it was spread later by war chronicles in the Edo Period. Even now you can clearly see how it goes in the castle ruins area from Odawara city area where Hojo was.

城周辺の地図~The map of around the castle

小田原城址から見た石垣山城~Ishigakiyama Castle from Odawara Castle Ruins

Though the castle has such an unclear story, it is still worth the visit, because it is the first castle made up entirely of stone walls in eastern Japan. Until then, it was common to build castle foundation mainly from soil in the area. Hideyoshi first stayed at a temple for the siege from April 6 in 1590, then started to build the castle right away, bringing the specialists of piling stone walls called Anoushu. He moved to the castle as his stronghold on June 26. That means the castle was built in less than three months. It can be seen as a surprisingly short term to build a formal castle at that time.

豊臣秀吉肖像画、加納光信筆、高台寺蔵~The Portrait of Hideyoshi Toyotomi, attributed to Mitsunobu Kano, owned by Kodaiji Temple(licensed under Public Domain via Wikimedia Commons)

Many historians and writers say the castle demonstrated Hideyoshi’s authority to Hojo and his supporters. Some point out that the castle would be for a longer term siege. The fact was that Hojo surrendered on July 5, but it was uncertain before then. Old documents say Hideyoshi’s soldiers got bored and supplies were getting less. There is another evidence that the construction was going on after the siege. The Tokugawa clan, following Hojo, seemed to use the castle for a while. Roof tiles for the Tenshu keep with newer dates than the siege were found by excavation. After that it seemed to be abandoned for sometime.

城周辺の航空写真~The aerial photo of around the castle


Even now, you may be surprised to see there are the castle ruins with such large stones, to say nothing of the people at that time. Visitors usually go up from the parking area to the Ninomaru enclosure through the South enclosure. You can see a lot of half collapsing stone walls alongside. They look rough but regal.

南曲輪の石垣~The stone walls of South enclosure
崩れかけた石垣~The half collapsing stone walls
二の丸~Ninomaru enclosure

Don’t miss to see Ido enclosure which was used for the well. It is totally covered with piled natural stones along the corn shape of the well. It is very beautiful and shows the high level technique of Anoushu.

井戸曲輪~Ido enclosure(licensed by Tak1701d via Wikimedia Commons)

You can enter the North Gate Ruins of the Honmaru enclosure if you turn back to Ninomaru. There was Hideyoshi’s palace where he is said to hold a tea ceremony around. You can see the whole view of Odawara City including Odawara Castle. It served as Hideyoshi’s stronghold.

北門跡から見た本丸石垣~The stone walls of Honmaru enclosure from North Gate Ruins
本丸~Honmaru enclosure
本丸からの眺め~A view from Honmaru

The Tenshu ruins are next to Honmaru, but they don’t look so now. Their stone walls seemed to collapse due to Great Kanto Earthquakes. Lastly you can go down through the Main Gate Ruins and reach the East Entrance.

天守跡~The Tenshu ruins
大手門跡~The Main Gate Ruins
大手門跡から見た南曲輪~South enclosure from Main Gate Ruins

その後~Later Life

In the first 18th century in the Edo Period, the Ariura clan of the Odawara Domain investigated the castle ruins and left the drawings of the ruins. According to the drawings, the stone walls still kept well. But unfortunately Great Kanto Earthquakes in 1923 broke many of them. They were designated as a National Historic Site in 1959.

本丸の石垣~The stone walls of Honmaru enclosure

私の感想~My Impression

I think one of the greatest things of the castle is its name “Ishigakiyama”. It just means a stone walls castle. It shows how surprisingly people at that time felt. The castle must have had a big impact on them. That’s why the name of the mountain was changed from Kasagakeyama to Ishigakiyama. The new name spread to the public at the latest in the mid Edo Period. It was probably combined with the Ichiya-jo story, and have fixed.

本丸からの眺めをもう一枚~Another view from Honmaru

ここに行くには~How to get There

It is useful to access Ishigakiyama Castle Ruins by car. It is several kilometers from the Odawara IC on Seishou Bypass or the Odawara-Nishi IC on Odawara-Atsugi Road. When using train, it takes about 40~50 minutes on foot from JR Hayakawa Station. It needs to climb up a steep slope, but it may be interesting.
From Tokyo to Hayakawa Station: Take the Tokaido Shinkansen super express to Odawara, then transfer to Tokaido local line.

早川駅からの坂道~The slope from Hayakawa Station
坂道から見た小田原城~Odawara Castle from the slope

リンク、参考情報~Links and References

石垣山一夜城、小田原市オフィシャルサイト~Odawara City Official Website
石垣山一夜城、小田原城街歩きガイド(Only Japanese)
・「関東の名城を歩く 南関東編/峰岸純夫、齋藤慎一編」吉川弘文館(Japanese Book)
・「よみがえる日本の城2」学研(Japanese Book)

投稿者: Yuzo

城巡りが好きなYuzoです。日本には数万の城があったといわれています。その内の200名城を手始めにどんどん紹介していきます。 I'm Yuzo, I love visiting castles and ruins. It is said that there were tens of thousands castles in Japan. I will introduce you top 200 castles and ruins of them, and more!

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