Naegi Castle

Naegi Castle is located in the Naegi district of Nakatsugawa City, Gifu Prefecture, Japan. Also known as Kasumi Castle ("Mist Castle"), it once served as the administrative center of the Naegi Domain and is now designated as a National Historic Site of Japan. Built on Mount Shiro overlooking the northern bank of the Kiso River, the castle made exceptional use of the natural rocky terrain, making it one of Japan's most distinctive examples of a mountain castle.

The castle's central enclosure covers approximately 20,000 square meters, while the entire castle complex, including the outer enclosures, extends across roughly 350,000 square meters. In 1981, part of the site was officially designated as a National Historic Site. From the banks of the Kiso River to the ruins of the main keep at the summit, there is an elevation difference of approximately 170 meters, giving the castle both formidable defensive advantages and spectacular panoramic views.

Because the castle was constructed atop a rugged rocky mountain, there was very little level ground available for building. As a result, many of its structures were erected directly on massive natural boulders, incorporating architectural techniques such as kake-zukuri (overhanging construction) that adapted buildings to the terrain. The castle's stone walls also display a variety of masonry styles, reflecting the advanced engineering methods developed to accommodate the site's challenging landscape.

Naegi Castle is also associated with the legend of the "Red Wall Castle." According to local folklore, the castle walls were originally coated with white plaster. However, a giant dragon said to inhabit the Kiso River despised the color white. Whenever the walls were freshly replastered, the dragon would summon fierce storms that stripped away the plaster, eventually exposing the reddish-brown earthen walls beneath. This is said to be the origin of the nickname "Red Wall Castle." The tale was later recorded in a local newspaper as a folk story, describing how the domain lord spent a night in the castle keep and personally witnessed the dragon appearing and blowing away the castle's white walls.

Historical research, however, generally concludes that the true reason behind the castle's distinctive reddish appearance was far more practical. The Naegi Domain faced chronic financial difficulties and could not afford the high cost of covering the castle extensively with white plaster. During the late Edo period, despite possessing an income of only 10,000 koku, the domain continued to maintain a full-fledged castle, forcing its rulers to manage and preserve the fortress under severe financial constraints. This combination of historical reality and enduring local legend has become one of Naegi Castle's most fascinating characteristics. Today, the castle ruins preserve not only the mountain fortress's original topography and stonework but also its unique architectural ingenuity and rich historical significance, making Naegi Castle one of Nakatsugawa City's most important cultural landmarks and tourist attractions.