Hoshiyamako Castle
Hoshiyamakojō ('Star Mountain Old Castle') is a yamajiro (mountaintop castle) ruin in Mukawa Township, Hokuto Municipality. Ruins consist of earthworks, including horikiri (ridgeline trenches) and tatebori (climbing trenches). Some sources show the location of Hoshiyamakojō as being too low down.
History
Hoshiyamakojō was built as a hidden mountain redoubt for the people of Mukawa to protect themselves in times of conflict, whenever a rampaging army came through the area, whether it be Takeda, Oda, Hōjō or Tokugawa. The castellan may have been Yanagisawa Hyōbu, a member of the Mukawa-shū, a local war band. When Oda Nobunaga conquered Kai in 1582, Hoshiyamakojō is where defenceless villagers sheltered from the bloodlusting Oda forces, and accounts describe the elderly, women and children hiding in the shadows of rocks deep in the mountains.
Field Notes
Hoshiyamakojō ('Star Mountain Old Castle') is a yamajiro (mountaintop castle) ruin in Mukawa Township, Hokuto Municipality. Ruins consist of earthworks, including horikiri (ridgeline trenches) and tatebori (climbing trenches).
Some sources show the location of Hoshiyamakojō as being too low down. The fort is located on the peak at 969m above sea level. There isn't much of a trail anymore, but the start is located behind a summer home in the hamlet to the northeast. There is a zigzagging old mountain path on the right side, climbing, of the ridge. The left side, that I took down, is heavily eroded with deadly drops and should be avoided.
The main bailey is readily recognisable as one approaches a large horikiri to its rear. There is a small pocket bailey directly above the trench, and the main bailey is above that. It looked to me as though the narrow, steep ridges beneath the peak could've been worked too, but the terrain was too risky to tackle in the gathering snow.
The horikiri divides the main bailey and second bailey. The second bailey is barely worked, but opens out into the expansive, sloping third bailey. It seems somewhat hollowed out as it climbs. This rudimentary working of the natural mount is perhaps indicative of an emergency refuge for the townsfolk. I walked up to above 1,000m looking for a definitive end to the bailey, and a little after it narrowed there was what looked like it might've been another trench separating two small peaks. By this time a flurry was dancing all around me so I decided to make my descent.
Gallery
| Castle Profile | |
|---|---|
| English Name | Hoshiyamako Castle |
| Japanese Name | 星山古城 |
| Founder | Yanagisawa Hyōbu |
| Year Founded | Sengoku Period |
| Castle Type | Mountaintop |
| Castle Condition | Ruins only |
| Historical Period | Pre Edo Period |
| Artifacts | Kuruwa, Horikiri, Tatebori, Dorui, &c. |
| Features | trenches |
| Visitor Information | |
| Access | Climb from hamlet to northeast |
| Hours | 24/7 free; mountain |
| Time Required | 50 minutes |
| URL | Castle Website |
| Location | Hokuto, Yamanashi Prefecture |
| Coordinates | 35.75834, 138.331 |
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| Admin | |
| Added to Jcastle | 2025 |
| Contributor | ART |
| Admin Year Visited | Viewer Contributed |
| Friends of JCastle | |
| Jōkakuzukan | |
