Sarukoya Fort


SarukoyaToride (1).JPG

Visit Notes

Descending and rising as the dragon in flight, hoary pinacles of rock rise from the ridge like great spikes on the back of the beast. The brave adventurer - that's me - bestrode that soaring dragon, and returned with the treasure of another conquered mountaintop castle!

That's my version of events and I'm sticking with it. But actually the ruins of Sarukoya-toride were not easy to find or climb to. I probably could've climbed up straight from Kakiagejō, but I had the wrong co-ordinates, and so descended and re-ascended via another ridge. I searched high and low but found no ruins, and it was then I determined that I had got the wrong ridge and my marker was inaccurate. To reach the next ridge I could've descended or gone right to the top of the mountain which loomed above. I chose the latter option and it was well I did. My suspicion at that point was that the castle ruins may terminate at the peak, climbing from the ridge opposite Kakiagejō, but when I got to the peak I saw it was just the beginning of the long, undulating ruins of Sarukoya-toride. I knew that because I had a map so that I could identify which bailey I had arrived in. To reach the end of the castle I still had to traverse the ruins, but that was the fun part after so much slogging upward!

There are five groupings of narrow baileys straddling the ridge, and each is separated by either a trench, a drastic increase in elevation, or both. The fifth, lowest bailey has several sub-baileys beneath it, and a boomerang-shaped trench which is where I first recognised and entered the fort area. Impressive rock formations help protect the third bailey and much of the first bailey, and the latter bailey is the highest but smallest. Parts of the ramparts of the first bailey look also like they may have been augmented with stone piles, though mostly they are composed of the rock of the mountain itself. Between the fourth and third bailey is a trench which is quite wide as it slopes off down the mountain, and this seems to be augmented natural terrain. Between the third and second bailey, however, human hands have wrought a gigantic, fearsome trench*. At its centre is a sunken earthen bridge. I had not expected such impressive defences this high up; was nature not enough?

Sarukoya-toride, 'Monkey Hut Fort', lives up to its name. As I said, it's both difficult to locate and difficult to get to. Castles called for monkeys are usually very high up, and so 'monkey castles' because only monkeys can get to them ('demon castles' are likewise). Though 'koya' means 'hut', in reference to mountaintop castles it refers to a small, hidden redoubt. 'Koya' is a misnomer here because the site is quite extensive. The use of 'toride' for 'fort' instead of 'castle' is probably because, firstly, the baileys are quite narrow, and, secondly, Sarukoya-toride was a branch fort serving Kakiagejō (though overall it seems Sarukoya-toride covers a larger area).

  • Ranmaru-sensei says that there is disagreement about whether this formation is a horikiri or a kirigishi. The overall effect is of a gigantic trench, but the difference between those two features is that a horikiri, a moat cutting, would have to be dug from a level ridge, whereas a kirigishi, carved slope, would augment a pre-existing natural depression (could it be a mix of the two?). The exact manufacture would be important to determine to know how important the fort was considered, but since the end result is of a big trench, I describe it that way above. To be fair, I can see why Ranmaru-sensei and Lord Teipisu go with kirigishi: (1) there are other trenches along the ridge which are much shallower, (2) such a high position would be difficult to work extensively and perhaps that would be needless, and (3) the second largest trench also seems only partially processed to me. Ranmaru-sensei says he is in opposition to 'god' here, and I presume he means Miyasaka Takeo, the renowned researcher of fortifications in Shinano.


Castle Profile
English Name Sarukoya Fort
Japanese Name 猿小屋砦
Alternate Names 猿こや砦
Founder Ogasawara Clan or Takeda Clan
Year Founded Sengoku Period
Castle Type Mountaintop
Castle Condition Ruins only
Historical Period Pre Edo Period
Artifacts Horikiri, Kirigishi, Dorui, Ishidzumi
Features trenches
Visitor Information
Access Bus from Matsumoto to Shiga
Visitor Information 24/7 free; mountain
Time Required 40 minutes
Location Matsumoto, Nagano Prefecture
Coordinates 36° 18' 21.74" N, 138° 1' 16.39" E
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Added to Jcastle 2022
Contributor ART
Admin Year Visited Viewer Contributed
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