It is said that Muraijō was the fort of Tezuka Mitsumori, a vassal of Minamoto Yoshinaka. The Murai Clan are also thought to have later inhabited the site from the Kamakura Period onwards, which was where the fort got its name. During this time Muraijō would've been the site of the clan's main fortified residence (yakata) on the plain, and Sugawarajō served as a branch castle. In 1548 Takeda Shingen went to war against Ogasawara Nagatoki. Muraijō belonged to Ogasawara and was used to defend central Shinano. Ogasawara was defeated at the Battle of Shiojiri Pass (located to the south of Muraijō) and the castellans of Muraijō, the Murai Clan, were wiped out. Takeda Shingen conquered Muraijō and used it to advance upon and capture Hayashijō. In 1550 Hayashijō fell and Muraijō, being replaced by Fukashijō (later renamed Matsumotojō), was abandoned. No ruins remain.
The former site of Muraijō / Koyajō was on my way back home from another site, Momose-jin'ya, so I stopped by, but otherwise I wouldn't've bothered. Absolutely nothing remains of the fort. The only clue as to its existence is a signboard detailing the history of the site. The land is now occupied by maisonettes. Comparing my pictures online with others I noticed that a small wooden marker is now missing. That is the most significant thing I can report. I was surprised to find that Muraijō has its own wikipedia article (in Japanese)! So I've translated that for the history section above.
I've called it Koya-yakata as the main name for this article because that's how I found it first and because maybe there's a much better Murai Castle or Koya Castle worthy of taking up the name on this website somewhere.
|English Name||Koya Yakata|
|Alternate Names||Muraijō / Koyajō|
|Year Founded||Kamakura Period|
|Castle Type||Fortified Manor|
|Castle Condition||Ruins only|
|Historical Period||Pre Edo Period|
|Access||Murai Station on the Chūō Main Line; walk 5 minutes|
|Visitor Information||24/7; free|
|Time Required||Thirty Seconds|
|Location||Matsumoto, Nagano Prefecture|
|Coordinates||36° 10' 39.50" N, 137° 57' 17.46" E|
|Added to Jcastle||2019|
|Admin Year Visited||Viewer Contributed|