Ojima Castle (Mino)
Ojimajō is a yamajiro (mountaintop castle) ruin in Ibigawa Township, Ibi County. Maybe the descriptor 'mountainside' rather than 'mountaintop' works better for Ojimajō since the castle's most prevalent structural feature is the seemingly endless bands of terracing stretching all the way up to the to
History
Although not confirmed, it is traditionally held that Ojimajō was first built by the Nishio Clan circa 1315. Ojimajō is first attested, at least in some form, from 1337 when it was held by the Southern Court against a siege by Northern Court forces; the Southern Court lost the castle. This battle was fought at Kidonô, or 'Wood Gate Ridge', and Ojimajō is built on Kido ridge, and is also called Kidojō. It's not clear to me whether Ojimajō wasn't just a temporary ridgetop fort at that time, and the main residential castle wasn't in fact Kamigarejō on the plateau to the west.
After the courtly wars, Ojimajō (or, Kamigarejō) became the residence of Toki Yoriyasu, the governor of Mino, Owari and Ise provinces. In 1390, Ojimajō, then controlled by Toki Yasuyuki, was attacked by Kyōgoku Takahide, governor of Ōmi, under the orders of the Muromachi Shogunate, and fell.
Ojimajō disappears from the historical record from 1390. Yet the ruins, to me at least (and I dare say most yamajiro fans would agree with me), appear to be clearly from the Sengoku period. I think the Ojimajō known to history was likely centred around the live-in castle of Kamigarejō, and nearby ridges, such as Kidonô, were used in times of conflict as temporary redoubts. The ridgetop 'Ojimajō' was probably actually the Kidojō known to history. The Ojimajō whose ruins we see today was then built some time after the abandonment of this initial complex of forts and residences, and used in the wars of the 16th century, though it is not known by whom. It's possible that the Toki, Saitō and Oda clans all held the castle during the Sengoku period.
Field Notes
Ojimajō is a yamajiro (mountaintop castle) ruin in Ibigawa Township, Ibi County. Maybe the descriptor 'mountainside' rather than 'mountaintop' works better for Ojimajō since the castle's most prevalent structural feature is the seemingly endless bands of terracing stretching all the way up to the topmost bailey.
Features of Ojimajō include horikiri (trenches), tatebori (climbing trenches), ishigaki (stone-piled ramparts), dorui (earthen ramparts) and terraced baileys. Because of the extensive terracing throughout the castle's footprint the only none-terraced bailey is the topmost. This is called the first bailey, but probably didn't function as the main bailey, and was more like a look-out space. To the rear of here is the site's only horikiri, which bisects the ridge, and is wide, deep and sloping, quickly becoming tatebori like the rest of the hori (moats) found at the castle. Further, the castle's only dobashi (earthen bridge) spans this large moat, and is one of the longest dobashi I've seen at a yamajiro.
The lower baileys of Ojimajō now host a shrine to Kwannon. When I visited, the autumn colours at this altitude were effulgent. Naturally, the terraces narrow as they climb, though the second or penultimate bailey is quite spacious and appears to contain a stone-lined well. The upper castle is now mostly used as a cedar plantation. These terraces are bounded in the west by a huge tatebori stretching all the way down the mountainside.
I found three decent sized blobs of ishigaki throughout the ruins. The most impressive segment is squeezed between two short tatebori on the side of the upper bailey cluster. It looks like it must collapse totally one day, and already has in parts, but it is beautiful. It's hard to find so I'm glad I didn't miss it.
| Castle Profile | |
|---|---|
| English Name | Ojima Castle (Mino) |
| Japanese Name | 美濃小島城 |
| Alternate Names | Kidojō (木戸城) |
| Founder | Nishio Clan |
| Year Founded | c.1315 |
| Castle Type | Mountaintop |
| Castle Condition | Ruins only |
| Historical Period | Pre Edo Period |
| Artifacts | Dobashi, Dorui, Tatebori, &c. |
| Features | trenches, stone walls |
| Visitor Information | |
| Access | Nearest station is Ibi Station on the Yōrō Line |
| Hours | 24/7 free; mountain |
| Time Required | 80 mins |
| Location | Ibigawa, Gifu Prefecture |
| Coordinates | 35.47438, 136.49953 |
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| Admin | |
| Added to Jcastle | 2025 |
| Contributor | ART |
| Admin Year Visited | Viewer Contributed |
| Friends of JCastle | |
| Jōkaku Hōrōki | |
| Umoreta Kojō | |
| Yogo | |
| Jōseki Meguri Bibōroku | |
