Kibune Castle


AzumiKibunejouA (16).JPG


Despite the vast scale of Kibunejō its history is little understood. However, given the size and location, the castle remains we see today were likely the work of the Nishina Clan and their vassals. Since in times of conflict their manors on the plain would be exposed, Kibunejō was likely used as an effective redoubt to defend from.

Visit Notes

Kibunejō is a vast site. It is an Sengoku period earthworks mountaintop castle site with many features such as horikiri (trenches), dorui (earthen ramparts), kuruwa (baileys), koshikuruwa (sub-baileys), dan-kuruwa (terraced baileys which climb ridges in stair-like fashion), and so on. Kibunejō is in many ways an exemplary yamajiro, and in others quite unique. Initially it is necessary to remark upon its size, as Kibunejō is one of Nagano Prefecture's largest yamajiro ruins. The castle can be rougly divided into two areas, the south and north castle, though the mountaintop is worked contiguously without any gaps in defences. It also has seven spurs of developed ridges, making the layout of the castle not unlike a squid with many grasping tentacles.

I mounted the ridge behind a temple called Jōfukuji and very quickly came upon evidence of terracing along it. I knew for sure I was on the right track when I encountered a small horikiri. Thereafter the ridge swept up quite drastically and with it came a marvellous climbing set of stair-like pocket baileys terracing the ridge with steep banks. At the top of these stairs is a complex of baileys. Three baileys are set in a row, one above the other, and the lowest of these is quite wide. To the south there is dorui with the remains of stone pilings scattered about, suggesting the use of some stonework. Beneath here is a spur along a lower ridge, which I did not look all of the way down (this castle ruin was too vast for me to cover every inch in just a few hours), though Yogo's map indicates there should be more baileys down here and a trench. The upper and middle bailey in this bailey group are impressive, and on the mountainside west of the upper terrace there is a large embankment or levelled peak which it is easy to imagine hosted a rudimentary tower or turret of some sort.

Already we can say that this would be about the size of a modest yamajiro by itself, but this is just the very doorstep of Kibunejō! Another bailey grouping, but taller and wider, with another large rear embankment is found following a deep moat, in turn another large trench beyond. I was staggered by this duplication of fortifications, but thereafter the castle widens out dramatically into a series of wide and long terraced baileys in between climbing ramparts. If barracks were built here they could've easily accomodated hundreds of men. This fascinating area, which Master Yogo describes like a "hinadan (doll stand)", unusual in its configuration for a mountaintop castle, is known as the otenjō (written as 御天上・御殿上), invoking the idea of a place of paramount importance. Actually I wondered how these terms might be related to tenshu (天守), getting me onto an etymological side quest...

The formation of this staggering array of earth is like the throne of a titan carved into the mountain. The amount of earth dug, moved, piled and flattened is mind-blowing. The surrounding countryside must've been denuded of able-bodied men to sculpt this abode of the gods.

A series of karabori (dry moats) and dorui interspersing yet more wide baileys gives way to what is considered the northern castle. The scenery is changed completely and we come into an area with ongoing forestry projects. A pylon sits on the hillside. The terracing here was either degraded, obscurred with recent activities, or never completed. Or some combination of those things. But above this terracing is a solid bailey complex. This area is sometimes considered the main bailey of the castle, surmounting the ultimate peak. The earthworks here are impressive. The bailey has dorui and is protected on three sides by deep horikiri. The easterly horikiri could swallow a house, and several trenches go off along a spur there; these were on my way to Aokijō and so I could check them all out.

To the north and northwest the extent of the site then doubles. After all that, there's so much more! How much of the mountain could possibly have been fortified? There is a bailey cluster to the north with some nice trenches along the site's most northerly spur. In general though the earthworks are less capably finished in these outer zones of the castle. It seems that the northern castle represents a later expansion which may not have been wholly finished. Indeed this site has many mysteries. Curiously this fascinating castle is little regarded, and until recently seems to have been completely forgotten, and has no designations or protections, which is very concerning. However, I am happy to report that newly minted signs indicating castle features have appeared throughout the site, and there is a sign pointing would-be adventurers in the direction of the castle from below near Jōfukuji. This is good news and tides that the ruins of Kibunejō may get more care and attention in the future.

  • Terraced sub-baileys climbing the ridge

Castle Profile
English Name Kibune Castle
Japanese Name 木舟城
Alternate Names Aźumi-Kibunejō
Founder Nishina Clan (probably)
Year Founded Sengoku Period
Castle Type Mountaintop
Castle Condition Ruins only
Historical Period Pre Edo Period
Artifacts Horikiri, Kuruwa, Dan-kuruwa, Koshikuruwa, Ishidzumi
Features trenches
Visitor Information
Access Shinano-Ômachi Station or Minami-Ômachi Station on the Ôito Line; 30 minute walk to trailhead at Jōfukuji
Visitor Information 24/7 free; mountain
Time Required 120 minutes
Location Ômachi, Nagano Prefecture
Coordinates 36° 29' 6.50" N, 137° 52' 37.24" E
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Added to Jcastle 2021
Contributor ART
Admin Year Visited Viewer Contributed
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