Reishōzanjō was the base of the Yaǵasaki Clan, thus the castle was also originally called Yaǵasakijō ('Reishōzan' came about in the Edo period after the castle was defunct, and the same clan name, Yaǵasaki, was also used for their other, later fort of Onibajō, and so Reishōzanjō may have had another name which has been lost to time). The Yaǵasaki, who also built Onibajō, served the Suwa Clan until 1542 when Takeda Shingen conquered Suwa. Thereafter the Yaǵasaki served the Takeda, and Reishōzanjō functioned as a satellite fortification of Ueharajō, and probably hosted a signal tower or some other means of sending smoke signals. The site of the Yaǵasaki Clan manor hall is not known, but it was presumably located on the plain somewhere between the mountain redoubts of Onibajō and Reishōzanjō.
Reishōzanjō is a small yamajiro (mountaintop castle) ruin situated on a 60m high ridge terminus overlooking the Suwa Basin. It has features such as horikiri (trenches), tatebori (climbing trenches), kuruwa (baileys), koshikuruwa (sub-baileys) and dorui (earthen ramparts). The main bailey is partially surrounded by dorui, and it has an 'L'-shaped koshikuruwa below. There is an outer bailey further up the ridge. The two principal baileys are divided by horikiri.
There is a walking path running through the satoyama biome between the ruins of Uehara Castle and Oniba Castle. I know because I used the path in 2020. I must've walked right beneath Reishōzanjō without realising it; I wasn't aware of these ruins at that time. From the forest path I just dashed up the side of the hill to get to the ruins as it was only about 40m more up. Anybody visiting here on foot would do well to follow the walking the route from Ueharajō as it's quite pleasant, being mostly flat and wooded.
|English Name||Reishouzan Castle|
|Alternate Names||Yaǵasakijō (矢ヶ崎城)|
|Year Founded||Sengoku Period|
|Castle Condition||Ruins only|
|Historical Period||Pre Edo Period|
|Artifacts||Tatebori, Horikiri, Dorui, Kuruwa, Koshikuruwa, &c.|
|Access||Nearest Station is Chino Station; there is a walking route from Uehara Castle|
|Visitor Information||24/7 free; mountain|
|Time Required||30 minutes|
|Location||Chino, Nagano Prefecture|
|Coordinates||36° 0' 2.88" N, 138° 9' 54.83" E|
|Added to Jcastle||2023|
|Admin Year Visited||Viewer Contributed|
|Friends of JCastle|