| John Asano

Hiking at the Oga Castle Ruins

This time of year is a great chance to get outdoors in central Japan to enjoy the warm weather and beautiful mountains. Landlocked Gifu Prefecture is home to a host of mountains, making it the perfect place to enjoy one of Japan’s most popular activities, mountain hiking. One of my favorite local hikes is the climb up Mount Kojo in Yamagata City, Gifu Prefecture. The mountain is where you will find the ruins of the once impressive Oga Castle.

Mount Kojo

The 407.5 meter-tall Mount Kojo is only a short 25 minutes north of downtown Gifu City. The mountain is known for its stunning panoramic views with the morning view from the top of Mount Kojo being designated as “One of Japan’s Top 100 Morning Suns”. The best time to see the spectacular sunrise is about 30 minutes before daybreak when the sky begins to brighten up.

Map of the Oga Castle Ruins

From the peak, visitors can experience amazing vistas of the surrounding area which includes nearby Mount Kinka in Gifu City as well as spots far off in the distance such as Ise Bay, Mount Ibuki and the skyscrapers of Nagoya in Aichi Prefecture.

The view from the top of Mount Kojo

In fall, this is one of the best spots in Japan to see unkai (a sea of clouds), which form below Mount Kojo when the timing and conditions are just right in the early morning.

The Oga Castle Ruins

The stronghold of Oga Castle once stood at the peak of Mount Kojo hundreds of years ago during the age of the samurai, where it towered over the prosperous castle town below. Today, unfortunately only a set of ruins remain and a cute 6-7 meter-high replica mini castle on the mountaintop, which was built by the local residents and is a symbol of pride in the area.

The replica mini castle tower at the summit

The ruins of the ishigaki (stone walls) and remaining structures along the trails to the top of Mount Kojo allow visitors to imagine what the mountain castle would have looked like back in its heyday.

Ishigaki stone walls 

The original castle was a solid fortress that consisted of a large moat and earthen moat along with stone walls to prevent enemies from easily penetrating the outer fortifications.

Dry moat near the base of the mountain

The History of Oga Castle

For more than 200 years ~ from the Muromachi Period (1336-1573) to the Sengoku (Warring States) Period, the Toki clan wielded their power from the heart of Mino Province (modern-day southern Gifu).

Oga Castle and the castle town below flourished under the leadership of Yorinari Toki (1502-1582), a samurai warrior, who was the head of the Toki clan, governors of Mino Province during the 16th century.

The Toki clan were forced to move their administration and political functions to the Oga area in Yamagata City after the great flood of the Nagara River in 1535.

Unfortunately, the original castle was destroyed as a result of intense fighting between the Toki clan and rival Dosan Saito (deputy governor of Mino) in 1542. Yorinari was forced out of Mino by Dosan Saito (1494-1556), who went on to become daimyo (feudal lord) of Mino.

Castle tower and view over Yamagata City

Climbing the Mountain

There are two different ways up the mountain. The Kenkyaku Hiking Course is the best but most time-consuming, taking around 60-90 minutes, while the Hajikami Hiking Course is the quickest at around 20-30 minutes.

The trailhead for the Kenkyaku Course

The Kenkyaku Hiking Course

This course is the long way up the mountain at about 2.1 km but offers hikers the best chance to spot some of Oga Castle’s interesting ruins as you make your way to the top.

More ishigaki stone walls along the trail

Park your car at the Mount Kojo base and walk along the forest road to the endpoint along the Oga Castle climbing sign. The course starts from the Mount Kojo Trailhead and takes around 60-90 minutes to reach the mountain peak depending on your speed and how long you take to enjoy the ruins.

Small parking area

The start of the hike is relatively easy and flat with a wide track, but it narrows in parts and can be quite slippery, especially after rain. The final ascent to the peak is very steep and rocky, so you really need to watch your step.

The start of the hike along the Kenkyaku Course

The Hajikami Hiking Course

This short 750-meter course is the quick way up and begins at the Hajikami Rindo Trailhead and finishes at the peak of Mount Kojo. It should take around 20-30 minutes to reach the top.

Both courses have steep sections, so make sure that you are dressed appropriately with long pants and hiking boots and bring plenty of water to rehydrate.

Tip: There are no vending machines in the area around the mountain, so make sure that you bring your refreshments with you.

Cute sign warning against starting fires

How to Get There?

The best way to get to Mount Kojo is by car. From Nagoya take the expressway to the Seki-Hiromi IC, where it is about a 21-minute drive to the base of Mount Kojo.

There is a large parking area at the Mount Kojo Base, which can accommodate around 50 cars and around 15 spaces at the top of the Hajikami Rindo Forest Road.

Panoramic view from the mountaintop

Wrap Up

It’s a perfect time to get outdoors and hit the mountains of Gifu in central Japan. Mount Kojo and the Oga Castle Ruins are the best spots to enjoy the sunshine and outdoor charm of Gifu Prefecture.

Oga Castle in Gifu Prefecture

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