Ôsakijō is said to have been the castle of Shimizu Moriyoshi, a vassal of the Nishina Clan.
Ôsakijō sits on a mountain ridge just above a small hydroelectric powerplant. There is a nice switch-back path leading to the top of the ridge for accessing the plant’s reservoir but it is closed to the public. Castle explorers have no option but to assault the mountain head-on, or take a forestry road which runs to the castle from some place in the southwest. I climbed up the slope of the mountain to where the ridge terminates first to reach Ôsakidejō, the site of a satellite fortification of Ôsakijō, and then kept on climbing from there. There is no trail and the ridge has many large boulders.
Ôsakijō features hori (trenches), dorui (earthen ramparts), and kuruwa (baileys). There are at least three bailey groupings along the ridge, and the main bailey complex is situated forward. There are several earthworks around this main bailey area, including on the western slope where there is a very snug and cosy sub-bailey (it’s small, the size of a room) ensconced by dorui. There is a trench below here on the ridge spur. There are at least two trenches along the central ridge. After the final small bailey around the ridge, passing dorui and horikiri (trenches), I came to a flattened area which was clearly part of a forestry road. It’s possible the castle continued here but the ruins have been buried, but I don’t know.
|English Name||Ohsaki Castle|
|Year Founded||Sengoku Period|
|Castle Condition||Ruins only|
|Historical Period||Pre Edo Period|
|Artifacts||Horikiri, Dorui, Kuruwa, &c|
|Access||Climb from Dejō directly or take the old forestry road from the southwest|
|Time Required||40 minutes|
|Location||Ômachi, Nagano Prefecture|
|Coordinates||36° 28' 45.77" N, 137° 49' 40.98" E|
|Added to Jcastle||2022|
|Admin Year Visited||Viewer Contributed|
|Friends of JCastle|
|Shiro to Kosenjō|