[Historical Exploration] Narumi Castle Ruins: The Castle of Motonobu Okabe, the Fierce Imagawa General Who Held Out Until the End in the Battle of Okehazama

Narumi Castle was a castle that once existed in Midori Ward, Nagoya City, Aichi Prefecture, and served as an important stronghold for the Imagawa clan during the Battle of Okehazama. Oda Nobunaga built the Tange, Zenshoji, and Nakajima forts to surround and strictly monitor this castle.
Meanwhile, the commander defending Narumi Castle was the fierce Imagawa general Motonobu Okabe. Although he is not a widely known warlord, he continued to hold the castle even after Imagawa Yoshimoto was killed in the Battle of Okehazama, negotiated for the surrender of the castle, and succeeded in retrieving the head of his lord, Imagawa Yoshimoto.
In this article, we will introduce the history of the little-known battle at Narumi Castle and its related spots.

History of Narumi Castle

Narumi Castle was a castle that once existed in Narumi-cho, Midori Ward, Nagoya City, Aichi Prefecture, and is also known as Negoya Castle. Today, the site features the Tenjin Shrine to the east and Narumi Castle Ruins Park to the west, separated by the Narumi Kaido road.
Although almost no structural remains from that time exist, both areas are elevated above their surroundings, giving a sense of where the castle once stood.

The origins of Narumi Castle date back to the Oei era (1394–1428) of the Sengoku period, when the Ashikaga clan warrior Munenori Yasuhara relocated the Narumi Shrine, which had previously been enshrined in this area, to Mt. Otoko and built the castle.

During the Tenbun era (1532–1555), the castle was under the control of Nobuhide Oda (Nobunaga's father), and Noritsugu Yamaguchi, who served the Oda clan, was the lord of the castle. When Nobuhide died and Nobunaga succeeded as head of the family, Noritsugu suddenly defected to the Imagawa clan. He then made his son, Noriyoshi Yamaguchi, the lord of Narumi Castle.
In 1552, Noritsugu Yamaguchi brought in Imagawa-side warriors, prompting Nobunaga to mobilize his troops, which led to the Battle of Akatsuka. The battle ended in a stalemate, and it is said that it was resolved through the exchange of prisoners and horses.
However, the Yamaguchi father and son were later forced to commit seppuku by Imagawa Yoshimoto (one theory suggests this was because Yoshimoto feared that the Yamaguchi pair had sided with the Oda clan during the Battle of Akatsuka).

The next lord of Narumi Castle was the Imagawa-side warrior Motonobu Okabe. It is said that the 'Moto' in Motonobu was bestowed upon him from the 'Moto' in Imagawa Yoshimoto. Furthermore, Motonobu Okabe fought against the army of Nobuhide Oda (Nobunaga's father) in the Second Battle of Azukizaka in 1548 and contributed to the victory. Based on these facts, it is believed that he was highly trusted by Yoshimoto and was entrusted with the defense of Narumi Castle, which was the front line of the invasion of Owari.
Amidst such circumstances, Oda Nobunaga built the Tange, Zenshoji, and Nakajima forts within a 700-meter radius of Narumi Castle in 1559.

It was amidst this standoff that the Battle of Okehazama broke out in 1560. As is well known, Nobunaga killed Imagawa Yoshimoto. While other Imagawa-side warriors were killed one after another, Motonobu held out in Narumi Castle and continued to resist until the end. Motonobu then negotiated with Nobunaga and succeeded in retrieving the head of his lord, Imagawa Yoshimoto, on the condition that he surrender Narumi Castle.
After surrendering Narumi Castle, Motonobu Okabe returned to Suruga Province (present-day central and eastern Shizuoka Prefecture), the territory of the Imagawa clan. On his way, perhaps to avenge his lord Yoshimoto, he set fire to Kariya Castle (Kariya City, Aichi Prefecture) and killed the lord, Nobuchika Mizuno. It is said that Yoshimoto's heir, Ujizane Imagawa, was pleased with this action and gave Motonobu a letter of commendation.

After that, Nobumori Sakuma, a vassal of Nobunaga, and his son Nobuhide became the lords of Narumi Castle, but it is said that the castle was abandoned in 1590.
As for Motonobu Okabe, who was once the lord of Narumi Castle, he served Ujizane Imagawa until the Imagawa clan fell. He then served Shingen and Katsuyori Takeda. Furthermore, he was appointed as the castellan of Takatenjin Castle by Katsuyori, where he would go on to wage a siege battle against the forces of Tokugawa Ieyasu.

[Related Spots]

Tofuku-in Temple

This is a temple of the Chisan school of Shingon Buddhism, located about 100 meters northwest of the Narumi Castle ruins. It was originally located along the Kamakura Kaido and was rebuilt on this site during the Kanei era (1624–1644).
It is said that the temple gate was constructed using salvaged materials from Narumi Castle.

Narumi-juku Kosatsuba (Reconstruction)

Near the Narumi Castle ruins (on the Tenjinsha Shrine side), there is a reconstructed kosatsuba (official notice board), where five replicas of the original notices are displayed (the originals are kept at the Nagoya City Museum).
During the Edo period, Narumi was the 40th post station on the Tokaido, one of the Five Routes. In such busy post towns, laws and rules established by the shogunate or the daimyo were written in ink on these notice boards and displayed for the public.

Narumi Shrine

As mentioned above, the shrine was originally located on the site of Narumi Castle. Its founding is very ancient; it is said to have been established in the first year of Shucho (686 AD) when the Kusanagi no Tsurugi (the sacred sword) was returned to Atsuta, based on its connection to Yamato Takeru no Mikoto. It enshrines Yamato Takeru no Mikoto as the main deity, with his consort Miyazu-hime no Mikoto and her elder brother Takeinadane no Mikoto enshrined as associate deities.
It is said that before the Heian and Kamakura periods, the area around Narumi was a lagoon known as Narumi-ura (a shallow coastal area that would appear and disappear with the tides).
In the 40th year of Emperor Keiko's reign, during his eastern expedition, it is said that Yamato Takeru no Mikoto looked out from across the water toward the land of Hodaka (present-day Odaka, Midori-ku, Nagoya), where Otoyono Mikoto, one of the Owari no Kuni no Miyatsuko (local officials appointed by the Yamato government) and his daughter Miyazu-hime no Mikoto were said to live, and composed the poem: 'Looking at Narumi-ura, it is far away; shall I cross the Hodaka land in this evening tide?'

The above is an introduction to related spots, but as noted in the history section, there are also three fortresses built by Oda Nobunaga (Tange Fortress, Zenshoji Fortress, and Nakajima Fortress) within a 700-meter radius of the Narumi Castle ruins. Please be sure to visit these as well.