The location map at the site, with additional English names
The map around the castle
Today, the ruins of Okoh Castle is well developed as a historical park. If you drive to the park, you can easily park your car at the mid slope of the mountain near the entrance of the ruins. If you walk up on the slope from the entrance, you will first arrive at the front of the high earthen walls of the the castle.
The entrance of the castle ruinsThe remaining earthen walls at the ruins
From Forth Tier to Third Tier
Then, if you walk around to the right direction, you can enter the Forth Tier through the entrance of the enclosure called Koguchi. The entrance is made narrow and curved by the earthen walls for defense.
The entrance of the Forth TierThe inside of the Forth Tier
The Third Tier is higher than the Forth Tier, surrounding the Final Tier like belt. The strong stone foundations surrounded by stone-piled earthen walls remain inside the enclosure. The building on the foundations would have been an important structure for the castle.
The inside of the Third TierThe Third Tier surrounds the Final Tier like belt
Final Tier, Center of Castle
The Final Tier is the highest enclosure of the castle, so it was thought that it had the turret like a main tower. There are no building remaining on the ruins, but you can see a very good view of the Kacho Plain with lots of rice fields instead. You can easily imagine the area around the castle has been warm and rich.
Climbing up to the Final TierThe inside of the Final TierA view from the Final Tier
Second Tier to protect Final Tier
The Second Tier is opposite to the Forth Tier. The enclosure was separated by a ditch from the Final Tier to protect it. There is also a small enclosure named the Lower Final Tier between the Second Tier and the Final Tier, where another turret was probably built.
The Second TierThe ditch between the Second Tier and the Final TierThe Lower Final Tier
Okoh Castle was located what is now Nankoku City, Kochi Prefecture. The prefecture is one of the four prefectures in Shikoku Island, but separated by Shikoku Mountains from the other three northern prefectures. When the prefecture was called Tosa Province in the past, it was not easy to visit there. That’s why the province was sometimes used for one of the places for exile or escape. However, it has been easy to live for local people with a warm climate and abundant food.
The location of the castle
The relief map of Shikoku Island and the range of Tosa Province
Chosogabe Clan settled in Tosa and built Castle
Okoh Castle had been owned by the Chosogabe Clan during all its life. The clan has a very long history and it was said that their founder was a branch of the Hata Clan that came from Korea to Japan in the Ancient Times with advanced technologies such as civil engineering and silk industry. The Hata Clan spread them and moved from central Japan (now Kinki Region) to many local areas of Japan including what is now Nagano Prefecture where the founder of the Chosogabe Clan lived. The founder called Yoshitoshi Hata fought at Kyoto in the 12th Century, but was defeated, so he escaped from his enemies to Tosa Province. He finally settled near the provincial capital in the fertile Kacho Plain and changed his family name to Chosogabe by combining local land names. Okoh Castle was thought to be built on a mountain beside the plain at the same time.
The whole view of Okoh Castle Ruins (licensed by Saigen Jiro via Wikimedia Commons)
One of Chosogabe’s strengths was to have connections to central Japan such as serving the Hosokawa Clan, a senior vassal of the Ashikaga Shogunate and inviting the Ichijo Clan, a high class noble to Tosa Province as the provincial governor. As a result, the Chosogabe Clan became one of the seven ruling clans in Tosa in the first 16th Century. However, the others of the seven ruling clans including the Motoyama Clan were against the Chosogabe Clan, then they attacked and burned Okoh Castle in 1508. The trace of the fire was found in the ruins of the castle. The Chosogabe Clan was once defeated.
The Second Tier, one of the enclosures which include the trace of the fire
Motochika Chosogabe ruled Shikoku based in this Castle
The next lord of the clan, Kunichika Chosogabe came back to Okoh Castle in 1518 with the support from the Ichijo Clan. He got his power by organizing a soldier group called Ichiryo-Gusoku who were usually farmers, but also soldiers with a Set of Armour in emergency. After that, he took revenge on his enemies by taking them as relatives or battles with the Ichiryo-Gusoku group. Kunichika’s son, Motochika Chosogabe was succeeded in governing the whole Tosa Province in 1575. Okoh Castle had been the home base of the clan. It was a typical mountain castle with many tiers covering the mountain. However, it had some unique features coming from the Chosogabe Clan. It was thought that some turrets were built on stone foundations, using roof tiles made by craftsmen from Izumi Province (now part of Osaka Prefecture). Stones were piled inside the earthen walls of the Third Tier. Such structures were still rare at that time in the whole cuntory and were done by Motochika’s connection to central Japan.
The figure of a Ichiryo-Gusoku soldier, exhibited in Kochi CastleThe portrait of Motochika Chosogabe, owned by Hada Shrine (licensed under Public Domain via Wikimedia Commons)The stone walls of the Third Tier
Abandoned after Unification of Japan by Hideyoshi Toyotomi
Motochika finally achieved the unification of Shikoku Island in 1585. However, the ruler, Hideyoshi Toyotomi was processing his unification of Japan at the same time. Hedeyoshi sent over 100,000 of modernized troops to Shikoku Island in the same year while Motochika had about 40,000 soldiers including farmers. Motochika had no other option but to surrender and was allowed to govern just Tosa Provence by Hideyoshi. He also moved his home base from Okoh Castle to Otaka-sakayama Castle (now Kochi Castle) in 1588 and finally Urado Castle beside Urado Bay in 1591. it was said that this transfer was instructed by Hideyoshi to prepare his Invasion of Korea in 1592. Okoh Castle was abandoned then.
The Portrait of Hideyoshi Toyotomi, attributed to Mitsunobu Kano, owned by Kodaiji Temple (licensed under Public Domain via Wikimedia Commons)The present Kochi CastleThe ruins of Urado Castle
Local people are maintaining the ruins for visitors.
Later History
The ruins of Ichinomiya Castle were designated as a Prefectural Historic Site of Tokushima Prefecture in 1954. Since then, the local Society for the Preservation of the ruins has been developing them such as maintaining the trail and cutting the grass regularly. That’s why we can always visit the ruins in a comfortable environment. Tokushima City has also been researching the ruins since 2017. The foundations of the castle buildings were found and how the castle was developed is being revealed.
The well-developed trailThe artificial steep cliff under the primary enclosuresThe stone walls of the Main Enclosure
My Impression
After visiting the three most popular castle ruins in Tokushima Prefecture, I noticed that they all once became the capital of Awa Province – Shozui Castle (up to1582), Ichinomiya Castle (from 1585 to 1586) and Tokushima Castle (from 1586). However, they also all have quite different features from each other. This is because the situation of Awa Province changed greatly in a very short time. The needs for castles also changed rapidly at that time. I recommend visiting the three castle ruins and comparing them.
If you want to visit there by car: It is about 20 minutes away from Aizumi IC on Tokushima Expressway. You can park at the Ichinomiya Shrine or the Dainichi-ji Temple. By public transportation, take the Tokushima Bus on the Kamiyama Line bound for Yoriinaka from JR Tokushima Station and get off at the Ichinomiya-fudasho-mae bus stop. If you go there from Tokyo or Osaka, I recommend traveling by plane or using an express bus.
