The visitor center has a pamphlet (200 yen), a 100 Famous Castles stamp, and restrooms.
There's also an exhibit about Oni Castle, so it's best to check it out before visiting.
There's plenty to see.
I went all the way to the folding screen stone wall.
The view was amazing! 🎵
Due to time constraints, I skipped the North Gate, but it took about 80 minutes.
The walking trail is well-maintained, but there are many stones and some areas are slippery, so trekking shoes are a must.
Also, the stone wall is located at a high point, but there are no fences, so be careful!
If you just want to see the West Gate, it takes about 30 minutes.
But if you're a castle lover, it's a shame to miss just the West Gate.
The ruins of Oni Castle are located in Kuroo, Okusaka, Soja City, Okayama Prefecture. This is an ancient mountain castle built on Mount Onijo (approximately 400m) in the northern part of Soja City. While not mentioned in the Nihon Shoki (Chronicles of Japan), it is believed to have been constructed around the late 7th century. The prevailing theory is that it was built by the Yamato Imperial Court. It is now a National Historic Site and one of Japan's 100 Great Castles! I had visited the site once before, but I came here to get my stamp! Since I got my stamp at the Soja City Archaeological Museum in Soja City on a holiday, I wanted to see it again, so I returned! You can also get a stamp at the Mount Onijo Visitor Center! A highlight is the magnificent view of Soja City from the cliffside west gate!
I parked my car in the parking lot at Mt. Kinjo Visitor Center and took a walk. I was a little worried because I heard the road to the visitor center was narrow, but there were more passing points than I expected, so I managed to get there. The course took me from the visitor center to the West Gate, First Water Gate, Second Water Gate, South Gate, East Gate, Second Observation Deck, Byobu-ore Stone Wall, and North Gate. The footing was better than I expected, so I was able to get around without any difficulty. The Kannon statue along the way was very beautiful. The view was also good, as the trees around the observation deck had been cut down. Maps are sold at the visitor center for 200 yen, but you are allowed to take photos, so I used photos instead. It was even more wonderful than I expected. Thank you very much.
July 6, 2025
The remains of an ancient mountain castle stretched from Kuroo to Okusaka in Soja City. The castle grounds cover an area of approximately 29 hectares, covering the entire 397m-high Mount Onishiroyama area, with walls stretching a total distance of 2.8km.
While the details of this mysterious historical site remain unclear due to the lack of written records, it is said to be the location of the well-known Momotaro legend.
There's plenty to see here.
The Kokoroishi-like stone formations found on Mount Takara in Kurume City, Fukuoka Prefecture, the rare paving stones—the only ones of their kind in Japan (and one of only a few on the Korean Peninsula), the remains of a water gate, a restored west gate, the remains of a corner tower (restored), and the castle walls. Easy-to-understand explanations and maps are provided, making for a meaningful tour even without prior knowledge.
Because it's a mountain castle, the views are outstanding.
If you're short on time, a visit to the visitor center, west gate, paving stones, and the remains of the corner tower should suffice. Even then, it will take about an hour.
If you're a castle enthusiast, two hours will be a tough time for you if you make the full circuit, stopping off at the visitor center and sightseeing. There are many areas where the ground is rough, so hiking boots or sneakers are recommended.
Access is difficult unless you have a car.
Car navigation systems will show it as a one-hour drive from Okayama city, but from around Sunagawa Park at the foot of the mountain, the roads narrow and there are places where it's difficult for cars to pass each other, so be aware that it may take longer depending on traffic.
There is a large parking lot at the visitor center, and from there it's a walk. There are toilets at the visitor center, but not on the castle grounds.
From the visitor center to the west gate, we walked clockwise around the folding screen stone wall.
The view of the Bitchu Plain from the west gate and folding screen stone wall was particularly spectacular. It took about an hour to go around once.
🐻There were apparently no bears.
