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Japan Castles On The Air (JACOTA)

Castle 10 Yamato Koriyama castle

Greg Cook, JO3SLK

Introduction to Yamato Koriyama castle

I used to live in Oji, in Nara prefecture, not far from Koriyama castle…but I never visited the castle. That was before I started the “JACOTA” project. But the area and castle have a lot of history associated with them, so I decided to make Yamato Koriyama the 10th castle in this series. The official castle name is Yamato Koriyama, but most people just say Koriyama, so that is what I will call the castle in this article.

I now live in Kawanishi city, Hyogo prefecture, so it is about an hour and a half drive from my home to the castle. I left around 6:30am on a Saturday and took the expressway around Suita finally taking the Nara exit. I then followed the expressways and local roads, and arrived at the castle at 8:30am. The weather was very nice, with some clouds and sunshine. I found a small parking lot right next to the main castle gate, loaded my LC-192 backpack with the IC-705 inside, my Buddipole® antenna system bag and the pouch with my ID-51 inside onto my luggage carrier. The carrier has a built-in seat, which makes it nice when operating outdoors. The pouch I use was featured in the July issue of FB News.

The walk from my car to the Tenshudai (castle keep foundation) took about 10 minutes, and then a short climb up the steps to the top where I would operate. I set up the antenna, tuner, and rig, and was ready to go about 9:00am. But let us begin with information about Koriyama castle.

History of Koriyama castle

Koriyama castle was the single fortress structure in what was called “Yamato” prefecture in the Tensho era, between 1573 and 1592. Tsutsui Junkei took over the fort in about 1580. The actual castle construction was started in about 1585. Final construction of the outer moat was completed in 1595, and the castle grounds now are basically the same as they were at that time.

The castle was abandoned after the famous battle of Sekigahara, which changed the political structure of Japan. But the new Shogun thought the castle’s location close to Osaka and Kyoto was important, so he ordered reconstruction to begin in 1615. The castle changed hands several times later, but the Yanagasawa clan resided in the castle during the stable time of the Edo period, and it prospered economically and politically during that time.

Additional history

After Tsutsui Junkei defeated his long-time enemy Matsunaga Hisahide in 1580, he moved to Koriyama strengthening the fortifications that were there and building Koriyama Castle. In 1585 Hideyoshi's brother Hidenaga moved into Koriyama Castle and conducted many improvements making it into a large-scale modern castle. He also confiscated many stones from nearby temple gardens and even religious statues for use in the walls. Mashita Nagamori moved into the castle in 1595 but abandoned it when he lost at the Battle of Sekigahara. The castle fell into disrepair for a time until Ieyasu Tokugawa stationed Mizuno Katsushige here in 1615 and commissioned him to reconstruct the castle. Yanagisawa Yoshisato became lord of the castle in 1724. The Yanagisawa clan continued to rule until the Meiji Restoration when the castle was abandoned.(Additional history courtesy of Jcastle at

Historical structures at the castle

Otemon Gate

A massive structure, with huge and heavy doors. The area above the door could be used for arms storage, and for soldiers to shoot down on any enemy trying to break-in.

Otemuko Yagura in front of the Otemon Gate

Another place for soldiers to shoot the enemy, through windows in the walls. Anyone approaching the gate had to enter this narrow space and became easy targets.

Inside the castle grounds through the Otemon gate

Once through the gate, enemy soldiers had to again turn to the left and climb a narrow pathway, leaving themselves vulnerable to being shot from the gate above.

Joshi Meiji era museum located just inside the Otemon gate

Moats and bridges

Ishigaki stone walls (left) and the moat (rignt) almost dry

The pictures show how deep the moat is, and how tall the ishigaki walls are. The castle has inner, middle, and outer moats, all surrounded by ishigaki walls. Samurai houses were built around the castle, and town person’s homes on the flat lands. The change from mountain top castles to hilltop castles allowed the founding of towns for housing, samurai protection and trade, in the lower land surrounding the hill.

A view of the Gokuraku bridge and the inner moat.

Newly constructed Gokuraku bridge.

It resembles the original bridge that is depicted in the castle brochure drawing, made from old documents. This is a new bridge, and not seen in most articles or brochures about Koriyama castle.

Special Cyprus trees were used in the construction

I heard that the cost was about 3+ million dollars, maybe more. Lots of ironwork post caps and braces, probably hand-made. Just inside the gate is where the guides are at, waiting to take visitors on tours.

Gokuraku Bridge leading to the Hakutaku Gate

The floor of the bridge as well as the posts and rails are all made of a special Cyprus wood. The wood is stained a special orange color. The grain of the Cyprus really stands out.

The Tenshudai (Castle keep foundation)

Renovated Tenshudai (keep foundation)

The foundation is all that remains of the great Tenshu at Koriyama castle. The walls were crumbling, so they were renovated. Many important discoveries about the construction of the Tenshu foundation construction were discovered during the renovation. There is a nice sloping stairway leading up to the top, using stones as steps. The handrails take away from the “ancient castle” image but are necessary for the safety of the visitors.

Views from the top

View from the top of the Tenshudai

The Joshi museum is in the background, with the Otemon gate and Otemuko Yagura to the right. Further to the right, is the Gokuraku bridge that goes over the moat.

Beautiful view of the Meiji era museum from the top of the Tenshudai. I really like Meiji era architecture. I would like to go back to Koriyama castle and visit the museum, because I was limited in the time I could spend during this visit.

Panorama view.

If you look carefully, you can see Mt. Wakakusa, the twin 5 story pagodas, and the Todaiji shrine in the background. The Tenshudai is about 81 meters above sea level, so it is a low “hilltop” castle. However, as you can see, the castle lord had a very good view of any “enemy activity” going on around him. This view would have been even better from the top of the actual Tenshu castle keep, which would have been several stories higher.

Operating from the Tenshudai

The Tenshudai where I operated

There are many uniformed volunteer guides that take visitors on tours of the castle, including the top of the Tenshudai. They are very knowledgeable about the castle, and even one sang an old era song to entertain the visitors.

Operating “station” in a corner of the Tenshudai

On the top of the Tenshudai, I build a vertical dipole (L style radial) with the Buddipole® system. The tripod is the lighweight version that I discussed in the June issue of FB News.

The antenna consisted of an 11” section of aluminum tubing, the VersaTee® feed base, and a long expandable whip. The radial is attached to the VersaTee® base and is the same length as the main element whip. I adjusted slightly for a low SWR and the let the AH-705 tuner make the match to the IC-705.

The ARRL 10 meter contest was on the day I operated, and I made a quick contact with a local station on 28.450. But the activity hadn’t started yet when I was ready, so I put an expandable 144/430 whip antenna on the IC-705 and made a few V/UHF contacts on D-Star, 2 meter FM and then switched to 2 meter SSB. As I mentioned in the December issue of FB News, 2 meter SSB is very popular in Japan, and it is fun to contact local hams that may know the castle, or have been to the castle before.

But I wanted to see what 10 meters would produce, so I reconnected the HF antenna and started hunting. There was not a lot of activity, but checking out the spectrum scope on the IC-705 showed some activity around 28.435, so I tuned there. A VK2 station was calling CQ and he came back to me the first time I called. He gave me the usual “59” signal report and then his call serial number 017 (I was his 17th contact). He was my 01 serial number, not only the first contact of the contest, but also my first DX contact with the IC-705. Knowing I was operating QRP (5 watts on battery power) he was kind enough to let me know my real signal report was 53. I was very pleased.

After some time had passed I found another station calling CQ, and then making a contact with another station. I waited until they had finished, and replied to the station’s QRZ call. Again, he came back to me on my first call and gave me 59 and his number of 007, his 7th contact of the contest. I was pleased to put an FK4 call in my log. Again, I was very impressed with how the IC-705 and Buddipole® antenna were working.

I am not a “contester” and have never submitted a contest log, but I do enjoy “hunting and pouncing” during a contest to see how my station setup is working, and whether or not I can compete with the “big guns”. It is a lot of fun, and I always learn some techniques and tips each time I participate.

Wearing masks when necessary is very common in Japan, even before the Corona pandemic. Now we wear them everywhere we go, especially where there are many other people nearby. Outdoors at a castle site is no exception, and all the visitor, guides, and I wore them. I would take it off to operate, but when visitors were around, I put it back on. This picture was kindly taken by one of the guides, who took time away from his tour duties, and seemed to know about amateur radio. He gave me lots of information about the castle, including some very nice bilingual brochures, and a detailed map.

Several of the visitors stopped by and asked me “is this amateur radio”, and so I explained, “yes it is”…and talked about JACOTA and the other castles I have visited. They were truly interested in and surprised about posting articles on the web about castles and ham radio. They also mentioned other castles that they had visited, and we had a nice time chatting.

The castle was getting a lot of visitors to the top of the Tenshudai, and even though I was off in a corner, I was still blocking their view and in their way of taking some pictures. It was also noon, and I had been there three hours. So, I packed up my gear, descended the steps and made the 10-minute walk back to my car. It was another 1+1/2 hour drive home, and I was tired, but it had been a really fun and productive day. I hope you enjoyed reading about it too.

Next JACOTA castle

Winter is going to be tough this year, according to all the forecasts, so I am sticking close to home again for the next JACOTA adventures. On the schedule are two castles in Hyogo and Osaka prefectures, Amagasaki castle and Kishiwada castle.

Amagasaki castle

Kishiwada castle

Which one will I go to for the next JACOTA project? Be sure to check out the next FB News issue to find out. Until then, best 73.

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