The Origins of Horikoshi Castle
The place name “Horikoshi” first appears in historical records dating back to 1337, during the Northern and Southern Courts period. One record mentions the construction of a fortified residence, or tate, at Horikoshi, suggesting that the location already had military importance at an early date.
However, many details about the appearance and structure of the early medieval fortification remain unknown.
In the latter half of the 16th century, Oura Tamenobu, who later became known as Tsugaru Tamenobu, was a retainer of the Nanbu clan, which controlled much of the surrounding region. Tamenobu sought independence and gradually expanded his power.
Horikoshi once again became an important base during this period. According to the official history of the Hirosaki Domain, Tsugaru Ittoshi, Tamenobu used Horikoshi Castle as his base in 1571 when he launched a surprise attack on Ishikawa Castle. This campaign helped open the way toward the unification of the Tsugaru region under his rule.
Tsugaru Tamenobu and the Castle’s Golden Age
Around 1591, Tamenobu was officially recognized as a feudal lord by Toyotomi Hideyoshi, and his control over the Tsugaru territory was confirmed. In 1594, he moved his main residence from Oura Castle to Horikoshi Castle and undertook a major reconstruction of the fortress.
This large-scale renovation transformed Horikoshi Castle into the political and administrative center of the Tsugaru domain. The castle continued to be used after Tamenobu’s death by his son, Tsugaru Nobuhira, the second lord of the domain.
In 1611, the Tsugaru clan moved its base to Takaoka Castle, now known as Hirosaki Castle. Horikoshi had therefore served as the Tsugaru clan’s principal residence for approximately 17 years during a crucial period in the formation of the Hirosaki Domain.
The Castle Layout Revealed by Archaeological Excavations
Horikoshi Castle was a flatland castle with the main enclosure, or Honmaru, at its center. Other enclosures, including the Ninomaru and Sannomaru, as well as an outer defensive area, were arranged in concentric layers around it.
The Honmaru had a distinctive pentagonal shape and was surrounded by earthen walls approximately three meters high and an inner moat measuring roughly 15 to 20 meters wide. Entrances on the eastern and western sides, together with wooden and earthen bridges, formed a carefully planned circulation system that combined defensive functions with practical access.
After Horikoshi Castle was designated a National Historic Site in 1985, Hirosaki City carried out extensive archaeological investigations between 1998 and 2013. These excavations uncovered numerous remains, including foundations of buildings supported by stone bases, gate remains, post-hole buildings, water moats, and earthen ramparts.
The discoveries have helped researchers gradually reconstruct the appearance of the castle following the major renovations carried out during the Bunroku period in the late 16th century.
Restoration as a Historic Park
Based on the results of the archaeological research, Hirosaki City began a full-scale restoration and preservation project in 2012. The project included the restoration of castle enclosures, moats, and earthen ramparts, with completed areas gradually opened to the public.
In April 2020, the entire historic site was opened to visitors. Today, people can stroll through the grounds and see the reconstructed landscape while learning how the castle was organized and imagining the activities that once took place here.
Horikoshi Castle Ruins Guidance Facility and Former Ishitoyatani Family Residence
On the eastern side of the historic site stands the Horikoshi Castle Ruins Guidance Facility, which provides visitors with a deeper understanding of the castle’s history and archaeological discoveries.
The building itself has an interesting history. It is a relocated and reconstructed traditional farmhouse known as the Former Ishitoyatani Family Residence, which once stood in Hamano-machi, Hirosaki. The house represents the traditional agricultural architecture and lifestyle of the Tsugaru region during the Edo period.
Relocation and restoration work was carried out from fiscal 2015 through fiscal 2018. In 2024, the building was designated as an Aomori Prefectural Treasure.
Inside, visitors can learn about the history of Horikoshi Castle and the results of archaeological excavations in an easy-to-understand format. At the same time, the traditional farmhouse allows visitors to experience aspects of everyday life and architecture from the past.
Souvenirs and Hands-On Experiences
The facility also sells original Horikoshi Castle souvenirs, including castle stamps known as Gojōin, tote bags, and postcards.
Visitors can also try an armor-wearing experience for an additional fee, allowing them to put on armor modeled after that worn by foot soldiers. This hands-on activity can be an enjoyable way for both adults and children to connect with the history of the castle.
The Historical Value of the Tsugaru Clan Castle Ruins
Horikoshi Castle Ruins is designated together with Hirosaki Castle Ruins and Tanesato Castle Ruins as the “Historic Sites of Tsugaru Clan Castles.” Considered as a group, these sites provide an important opportunity to understand the development of the Tsugaru clan from a regional power during the Warring States period into a major feudal domain of the Edo period.
Horikoshi Castle is particularly significant because it represents an important transitional period in Tsugaru history. It was here that Tamenobu established a major base after expanding his power, and it remained the clan’s principal residence during the years when the foundations of the Hirosaki Domain were being established.
A Quiet Historic Landscape in Hirosaki
Today, Horikoshi Castle Ruins lies amid a peaceful rural landscape, far removed from the conflicts that once shaped its history. The quiet surroundings make it possible to explore the site at a relaxed pace while imagining the castle’s former buildings, moats, walls, and daily activities.
For history enthusiasts, the site offers an opportunity to explore the story of the Tsugaru clan and the formation of the Hirosaki Domain. For first-time visitors to Japanese castle ruins, its restored layout and archaeological exhibits provide an accessible introduction to the structure and history of a Japanese castle.
A visit to Horikoshi Castle Ruins is therefore a chance not only to see the remains of a historic fortress, but also to follow the story of Tsugaru Tamenobu and the rise of the Tsugaru clan in northern Japan.