Saturday, November 18, 2017

Shirihachi-date Castle -Mysterious mountain castle at north edge of main land-

Shirihachi-date Castle

-Mysterious mountain castle at north edge of main land-



Name: Shirihachi-date castle (Shirihachi-date)
Alias: Shiriboro Chashi, Ushirogata castle
Place: Rokumaibashi Aomori city, Aomori
Location: 40.93416061843747, 140.61829077714796
Type: Mountain Castle
Built: 13th century
Remaining remnants: Clay walls and dry moats 

Brief History

Shirihachidate castle (尻八館) is built over a hill called as Suribachi-yama, one of about 160 meter height from hillside at Tsugaru peninsula, about 20 kilometer north from Aomori city. Tsugaru peninsula is one of two peninsula prolong northward in Aomori prefecture along with Shimokita peninsula, and north edge of Honshu main land.

Tsugaru peninsula is one of about 40 kilometer long and 20 kilometer wide, and west half of the peninsula is a flat land and muddy area formed by Iwaki-gawa river, On the other hand, east half of peninsula is occupied by Tsugaru mountain which consist of middle height and low height mountain, except for narrow coastal area of Aomori bay continues toward current Aomori city.

Castle site of Shirihachidate castle is east edge of Tsugaru mountains in the lower half of the peninsula. From castle site the scenery of Aomori bay is well seen, and this place could control two mountainous road which cross Tsugaru mountain and connect eastern half and western half. Because of these reasons, Shirihachi castle has importance for Ando clan which prospered at western half of the peninsula, both as a defense point and advancing fort.

Origin of Shirihachi castle

The origin of Shirihachi-date castle is unknown but it might be built in 13th century. Origin of Ando clan is unknown but it is said as a descendant of indigenous people of Tohoku region. It is said that Ando clan was a leader of sea clan which engaged in fishery and marine transportation around Tohoku region and south part of Hokkaido island. But as a naval clan they were not so stick to the land then the record of Ando clan is quite limited. 

After the fall of Oshu Fujiwara clan which dominated Tohoku region in 1189, Kamakura Shogunate sent their retainer to the region, but appointed Ando clan as the governor of Hokkaido island called as "Ezo island" at that time and let them govern current Tsugaru peninsula and Oshima peninsula at both side of Tsugaru straight.

In Muromachi era, Ando clan survived the conflict between two Imperial Household and prospered based on the profit from marine transportation between Hokkaido island and Honshu main land. Their economic base Tosa-Minato port was one of the largest ports in Japan at that era, continues over 2 kilometer along the sandbank between Sea of Japan and Lake Jusanko. Ando clan also resided Fukushima castle at the north shore of Lake Jusanko.

Shirihachi castle was built as a front fort of Ando clan to watch Aomori bay area, across Tsugaru mountain from their main base Tosa-minato port. Shirihachi castle spreads over narrow ridge prolongs northeast from the peak of the hill, including inner area at southwest and outer area at northeast exists at the both side of over 100 meter saddle point.

Structure of Shirihachi castle

Inner part at western half is a oblong shaped terrace of about 100 meter long and 50 meter wide. The structure of the area by processing its slope into shape wall and digging dry moat at important point such as the top of the oblong is the same as Chashi castles built by indigenous people. Inner part is a flat area with remnants of buildings, thus it might be used as a residence of the lord.

Contrary to inner part, outer part is more secure area with layers of terraces built over front side slope. Backside of the area is guarded by two layer of large dry moat, and small dry moats are built around each edge of the hill. As main road from hillside connects to the outer part, this part might be added later to protect inner part of the castle.

From hillside entrance to hilltop castle, many structures such as dry moat, folded roads or flat spaces are built over climbing roads. Especially the space named Umatateba contains clay walls and dry moats, but it is not clear if this space was the front fort of the castle or just a shrine of later period. Anyway Shirihachi castle is a Japanese style mountain castle at the northernmost point of main land, clearly different from neighbor indigenous forts.

Prosper and fall of Ando clan

In the end of 14th century, Michisada Ando (?-?), an younger brother of Morisue Ando (?-?) who was the leader at the peak period of original Ando clan, became the lord of Shirihachi castle along with neighbor Yomogida castle which might be used as a daily residence. Michisada used as a surname of Ushiogata, the name of the area, and became a major branch family of Ando clan.

But in 15th century, the power of Ando clan significantly declined. Foreign trade at Tosa-minato port declined by strictly limited foreign trade of Korean peninsula and Chinese continent, and the function of the port was damaged by piling sand. Furthermore, conflict of the South Court army and Muromachi Shogunate army at Tohoku region which gave freedom to Ando clan ceased by the end of 14th century. 

In the beginning of 15th century, Nanbu clan which governed Pacific Ocean side of current Aomori prefecture rapidly grew and started expansion toward west. At first the leader of Ushiogata Ando clan married with the princess of Nanbu clan, to keep peace with Nanbu clan.

Wandering and settlement

However, around 1430 and 1440, Ando clan suffered severe defeat before Nanbu clan and abandoned their main base Tosaminato port. Yoshisue Ando (?-1453) once retreated to Hokkaido island where Ando clan held influence and raised his army to retrieve their territory, but this raise failed then Yoshisue lost his live and the history of original Ando clan had ended. Shirihachi castle might be abolished at this time.

At this time Masasue Ando (?-1488), the son of Ushiogata Ando clan who was born from the princess of Nanbu clan, was captured by Nanbu clan then placed as a nominal leader of Ando clan. Masasue once followed to Nanbu clan then moved to Hokkaido island and lived at Kakizaki clan who reigned Matsumae peninsula as a magistrate of Ando clan in 1454.

Furthermore, two years later, Masasue Ando was invited by Minato Ando clan which was a distant branch family of Ando clan resided at current Akita city area, the entered Noshiro area of Dewa province (Akita prefecture). Masasue built huge Hiyama castle and started Hiyama Ando clan, one of two origins of Akita clan which finally survived as the lord of Miharu castle (Fukushima prefecture).

Afterward of castle

After its capture Tsugaru peninsula was kept by Nanbu clan over 100 years, but in 1580's Tamenobu Oura (1550-1608), the local lord under Nanbu clan, left Nanbu clan and became an independent lord. Tamanobu changed his surname to Tsugaru and became the feudal lord of Tsugaru domain, and Tsugaru peninsula was included in the territory of the domain.

Now all building was lost but structure of the castle generally remain over the mountain. A brilliant Chinese incense burner was found at the outer part by excavation shows the wealth and power of the lord. Although approach road is quite difficult to find, hillside part with parking and climbing route are prepared. Well built castle unlike neighbor primitive forts shows former power of diminished Ando clan and conflict against Nanbu clan, then ended its role and quietly stays at nature, with the name of northernmost mountain castle of Honshu main land.


30 minutes walk from JR East Tsugaru-sen line Ushirogata station to Yamajiro-Koen park. Another 30 minutes walk from the park to hillside castle. 30 minutes drive from Aomori Jidoshado Expressway Aomori interchange to the park via Route 290 bypass. Turn left at the sign board of Kubota farm machine and go along the way.

Related Castles

Hiyama Castle -Large size mountain fortress of Great Sunrise lord-
Miharu Castle -Castle of hermit in flower town of long history-
Fukushima Castle (Mutsu) -Castle protected mysterious medieval port-


Pictures (click to enlarge)

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