Onigajo Castle

While older maps (like this one from the Kyoto Castle Survey) indicate ruins primarily around the mountain’s summit and main enclosure, a newer map in 明智光秀の城郭と合戦 reveals additional ruins along the trail. Notably, there are two distinct koguchi (gate entrances) along the pat

History

Onigajō Castle (鬼ヶ城) is historically linked to the Akai clan, whose main stronghold was Kuroi Castle. While the exact lord of Onigajō remains uncertain, it may have been under the control of either the Akai or Naitō clans at different times. The castle likely functioned as a satellite fortification of the Akai, overseeing the expansive Fukuchiyama plain. Its significant elevation above the plain provided a formidable defensive advantage and sight lines across the entire region.

In 1575, following the surrender of Naitō Tadayuki to Akechi Mitsuhide at Kameyama Castle (Tanba), some Naitō retainers defected and sought refuge at Onigajō. The castle ultimately fell to Mitsuhide’s forces in 1579 during the second Tanba campaign.

Field Notes

While older maps (like this one from the Kyoto Castle Survey) indicate ruins primarily around the mountain’s summit and main enclosure, a newer map in 明智光秀の城郭と合戦 reveals additional ruins along the trail. Notably, there are two distinct koguchi (gate entrances) along the path, each accompanied by dorui (earthen embankments). The nearer koguchi features some remaining stonework. Just before reaching the first koguchi, hikers will encounter a series of terraced kuruwa (baileys) too.

This is a long steep hike, but the trail is clear and well marked making it a good trek. The trailhead begins at Kannonji Temple and diverges from a popular hiking route leading to Mt. Chōgatake, which may have hosted another satellite fortification. Originally, I planned to explore this area as well; however, despite the clear morning weather, afternoon rain clouds prompted a change in plans.

Access to Onigajō via public transportation is limited. The nearest option is a 5 km uphill walk from Gujo Station. I started here but treated myself to a taxi ride to reach the trailhead since it was my birthday. Despite providing detailed directions, the driver attempted to take me to a forestry road leading to an alternate trail he recalled from his school days, which would supposedly end up much closer to the summit than Kannonji Temple. Unfortunately, this trail appears to no longer exist, or the forestry road is inaccessible. The driver felt bad about the inconvenience and kindly offered a complimentary return ride to Fukuchiyama Station after my hike. Given the changing afternoon weather conditions, I very much appreciated the gesture.

History clarification: Some blog sources inaccurately state that Onigajō fell to Akechi Mitsuhide in 1575. However, Mitsuhide’s initial campaign in Tanba began in 1575 but did not reach Fukuchiyama until the second campaign in 1578–1579. Therefore, the fall of Onigajō is more accurately dated to 1579.

https://www.kyoto-be.ne.jp/bunkazai/cms/?page_id=1521

Map Courtesy of Kyoto Pref. Board of Education.
Not to be used without permission.

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Gallery

koguchi

Castle Profile
English Name	Onigajo Castle
Japanese Name	鬼ヶ城
Founder	Akai Clan
Year Founded	Muromachi period
Castle Type	Mountaintop
Castle Condition	Ruins only
Historical Period	Pre Edo Period
Features	trenches, stone walls
Visitor Information
Access	Gujo Station (Line), 5km walk; Fukuchiyama Station, Taxi
Hours	Mountain trails, open any time
Time Required	180 mins
Hiking Trail	View on Yamap
Location	Fukuchiyama, Kyoto
Coordinates	35.34203, 135.14213
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Admin
Added to Jcastle	2025
Contributor	Eric
Admin Year Visited	2024
Admin Visits	October 21, 2024
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