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Castle Yagi Castle

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Yagi Castle (八木城 Yagi-jō) was a Japanese castle located in the vicinity of Yagi, Nantan, Kyōto Prefecture and Kanzen, Miyamae, Kameoka. It is one of the three major castles in Tamba Province (丹波国), along with Kuroi Castle (黒井城 Kuroi-jō) and Yakami Castle (八上城 Yakamii-jō). The castle is associated with the Christian warlord Naitō Joan (内藤如安, 1550-1626).



In 1333, Naitō Akikatsu (内藤顕勝, also known as Sadafusa 定房) responded to Ashikaga Takauji's call to raise troops at Shinomura Hachimangū Shrine (篠村八幡宮) in Tamba and received the fief of Funai-gun for his success in battle. The construction of Yagi Castle started in 1335. In 1392, when Hosokawa Yorimoto (細川頼元) was appointed shugo (守護 steward) of Tamba, the Naito were made castellans (守護所) in place of the Hosokawa who served as kanrei (管領) in the capital. In 1431, the Naitō were formally installed as Tamba shugo by shōgun Ashikaga Yoshinori (足利義教, 1394-1441).

Later, in December 1482, Uehara Motohide (上原元秀) became the governor of Tamba Province, but in October 1493, after an altercation with Nagashio Yaroku (長塩弥六), he died in November of the same year. In 1495, it was written that "Hosokawa himself went to Tamba Province, and his guardianship was returned to the Naitō". It seems that Naitō Motosada took over the stewardship after the fall of Uehara Kataie (上原賢家), father of Uehara Motohide. From 1505 to 1521, Naitō Sadamasa (内藤貞正) served as shugo, succeeded by Naitō Kunisada (内藤国貞).

However, after siding with Hosokawa Ujitsuna (細川氏綱) and Miyoshi Nagayoshi (三好長慶), Yagi Castle became the scene of several battles and fell in September 1553; Kunisada was killed. Later, Matsunaga Hisahide's (松永久秀) younger brother, Matsunaga Nagayori (松永長頼), recaptured Yagi Castle. It is believed that Nagayori was one of the most trusted men in Miyoshi's army and instrumental in keeping Tamba in the hands of the Miyoshi clan for thirteen years. In August 1565, he was killed in a counterattack by Akai Naomasa (赤井直正).

Naitō Joan, Christian warlord

Yagi Castle was the residence of the Christian warlord Naitō Joan (内藤如安), who was subjected to religious suppression. This made it very difficult to establish the castle's history, as many records were deliberately rewritten or destroyed to avoid persecution. This is why Yagi Castle is known as "phantom castle" and why it is still subject to intensive historical research.

Naitō Joan's mother was the daughter of Naitō Sadafusa (内藤定房). She married into the Azai clan in Ōmi Province (modern-day Shiga Prefecture). When her husband died of illness, she returned to Yagi Castle with her child, named Yagi Gemba (八木玄蕃), Naitō Joan's brother-in-law and retainer. Joan's mother later married into the Hosokawa clan, but once again, she was bereft of her husband and returned to Yagi Castle. She remarried a third time, this time Matsunaga Nagayori (松永長頼, d. 1565), with whom she had two more children: Naitō Gorōmaru (内藤五郎丸), later baptised Joan, and his sister Naitō Julia (内藤ジュリア).

Around 1553, Hatano Motokiyo (波多野元清), the lord of Yakami Castle (八上城) in Sasayama, invaded Tamba Province. Naitō Kunisada, lord of Yagi Castle at that time, was killed in the Battle of Honmego (本梅郷の戦い), while Naitō Sadafusa was killed when Motokiyo's forces took yagi Castle. Kunisada's son Chikatsumaru (千勝丸) was rescued by Yuasa Munesada (湯浅宗貞) and brought to the safety of Sonobe Castle (園部城). Matsunaga Nagayori, angered by the fall of Yagi Castle, turned back from the battlefield and succeeded to recapture Yagi Castle. As a reward for his achievements, the shōgun granted him the surname Naitō, and he called himself Naitō Munekatsu (内藤宗勝).

Gorōmaru and his sister were raised by a woman named Catarina (カタリナ) who had fled a clan dispute in Yamaguchi, most likely the Taineiji Rebellion (大寧寺の変) of 1551, in which Sue Harukata (陶晴賢, 1521-1555) led a coup against the Ōuchi clan. Catarina raised Gorōmaru and his sister Julia as if they were her children, and it was her influence that both Gorōmaru and Julia were initiated into Christianity. In May 1565, Gorōmaru was baptised by Luís Fróis, a Portuguese missionary at the Namban-ji in Kyōto, and given the baptismal name Joan.

In the meantime, Akai Naomasa (赤井直正, 1529-1578), of Kuroi Castle (黒井城), also known as the 'Red Devil of Tamba', and Hatano Hideharu (波多野秀治, 1541-1579) of Yakami Castle, battled for the control of Tamba. In August of the same year, Matsunaga Nagayori set out with more than 700 soldiers. As they advanced to Hikami-gun, they camped at a nearby temple because it was raining heavily at nightfall. However, a priest tipped off Akai Naomasa, who attacked at night, killing almost all Nagayori's soldiers. It was just three months after Naitō Joan was baptised that his father was slain in battle.

After his father's death, Joan took over Yagi Castle and carried out missionary work in the region. He invited the Japanese friar Lorenzo Ryosai (ロレンソ了斎), a disciple of Luis Frois. Lorenzo is said to have converted some 6,000 followers from Kyūshu to Kyōto. He visited Yagi Castle twice, in 1572 and 1573. In early 1573, Gaspar Vilella wrote of his second visit: "Padre Organcino arrived here with Lorenzo from Sanga about eight days ago. He was waiting for Lorenzo in Tamba to hear his sermon, and the day before yesterday he left with the person who had come to receive him". On his third visit in 1574, an unpublished letter from Luís Fróis says: "At times, Frois followed the mountainous road from the capital to Tamba with Lorenzo. About two miles away, Joan Naitō met him with his retainers. The castle was decorated with a magnificent altar. In eight days, seventy soldiers and fourteen others received him. Yagi Castle was becoming a base for Jesuit missionary work in Tamba.

Around this time, a succession dispute between two factions flared up: one that supported Naitō Joan and the other that wanted to instate Chishomaru (千勝丸, later Naitō Sadakatsu), the son of Naitō Kunisada. Naitō Sadafusa's brother, a monk, used every opportunity to agitate against Matsunaga Nagayori, as he was not related to the Naitō clan. Joan's mother was pressured to give up the idea of making her son lord of Yagi, a demand she stubbornly refused. Eventually, she was killed in the autumn of 1573. Later, Joan became a kakushō (客将, a military commander treated as a guest without master-servant relationship) of Konishi Yukinaga (小西行長, 1558-1600), and served in the Japanese invasions of Korea (1592-1598). When the Tokugawa shogunate banned Christianity, he was exiled along with Justo Takayama Ukon (ジュスト高山右近, 1552-1615) to Manila where he passed away at the age of 73.

The Battle of Yagi Castle

In 1579, Oda Nobunaga's army, led by Akechi Mitsuhide (明智光秀), embarked on a second campaign to conquer Tamba Province, focusing on Yakami Castle and Kuroi Castle. In May of the same year, when Ayabe Castle (綾部城) and Tamamaki Castle (玉巻城) fell, Hashiba Hideyoshi (later known as Toyotomi Hideyoshi) sent Niwa Nagahide, Hashiba Hidenaga and others as reinforcements in the Siege of Miki (三木合戦, 1578-1580). In June of the same year, they sent Naitō Arikatsu (内藤有勝), who still held a certain amount of power in the area, to attack Yagi Castle. As Yagi Castle was built on a natural precipice, it could only be taken under great sacrifice, so Akechi Mitsuhide proposed a peace treaty. However, Arikatsu refused and challenged him to a defensive battle. Akechi Mitsuhide then tried to persuade the garrison of Yagi Castle to rebel against Arikatsu, and some of the Naitō troops defected and set fire to the castle's honmaru and ninomaru. The castle finally fell on 27 June of the same year. Naitō Arikatsu was killed in the battle.

Naitō Masakatsu (内藤正勝) tried to break through Akechi Mitsuhide's lines and head for Hatta Castle, but while fleeing, some of his troops committed suicide. Masakatsu made it to Kogadake Castle (鴻ヶ獄城), where he died. As a result, the Naitō clan, which had existed since the Muromachi period, died out. Some historians claim that Arikatsu was a fictional character. Due to the lack of historical records, Joan was during the Battle of Yagi Castle could not be established.

It is also unknown when the castle was abandoned. According to the historian Fukushima Katsuhiko, Yagi Castle was renovated by Akechi Mitsuhide. Mr Fukushima also points out that artefacts found when the National Road 478 bypass was constructed can, in all likelihood, be traced back to Akechi Mitsuhide. After the fall of the Naitō clan, Akechi Mitsuhide built Tamba Kameyama Castle, the new power centre of Tamba Province. Still, Yagi Castle survived as a branch castle of Kameyama Castle.

Visiting the castle:

Stone walls and enclosures remain on the top of mountains and ridges.


Based on the Aerial Photograph Searching Service of the Geospatial Information Authority of Japan. The location of the enclosures is estimated.

It had snowed the day before I visited the castle, and the mountains were still covered in white. I parked my car near Kasuga Shrine beside the Kyōto-Jūkan Expressway.

The monument of Naito Joan (内藤ジョアンの碑)


An underpass under the expressway is modelled after the castle.


The entrance to the castle is just behind this guardrail.


At any rate, we started to ascend, but there was still a surprising amount of snow on the mountain.

Taimenjo-kuruwa (対面所郭)

After the fifth station, there is a fork in the road, and if you take the road on the left, you will arrive at the Taimanjo-kuruwa. There is a long and narrow circle along the ridge.


When we reached the sixth station, we felt it was too daring to go further and turned back.


I felt it was a pity to give up, but it got me thinking about how soldiers in hilltop castles spent their time in winter. Hilltop castles are not just about being on steep terrain, especially in snowy areas, so I was puzzled how they kept out the snow and the cold.

Date of visit: 29 December 2013


  • Address: Yagicho Yagi, Nantan, Kyōto 629-0141
  • Access: to Kasuga Shrine, a 15-minute walk from JR San'in Line Yagi Station
    3 kilometres from Kyōto-Jūkan Expressway Yagi-Higashi Interchange via Prefectural Route 455
  • Parking: Kasuga Shrine Parking (free, see map above)
  • Other sights: Tamba Kameyama Castle
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Hiroto Uehara
Hiroto is an ordinary Japanese office worker, but his true mission is searching for castles on the weekend.


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Hiroto Uehara
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〒629-0141 京都府南丹市八木町八木

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