Nanao Castle

Nanao Castle, located in Kojōmachi, Nanao City, Ishikawa Prefecture, is a mountain castle built during the Muromachi period and expanded through the Sengoku period. It has been designated as a National Historic Site. The castle was initially expanded by the Hatakeyama clan of Noto Province, and at its peak, it was enormous—about 2.5 km from north to south and 1 km from east to west.

The castle site sits on the northern end of the Isurugi Mountain range at an elevation of about 300 meters (locally known as “Shiroyama”), offering panoramic views of Nanao Bay. The name “Nanao” (literally “Seven Ridges”) comes from the seven main ridges branching from the mountaintop—Matsuo, Takeo, Umeo, Kikkuo, Kameo, Torao, and Tatsuo. Historical records also refer to it as “Matsuo Castle” or “Sueo Castle,” since the main keep was located on the Matsuo ridge. The castle’s layout followed the ridgeline, forming a series of enclosures (kuruwa). The residences of the Hatakeyama clan and their senior retainers, the Yusa and Naga clans, were located in the central enclosures, with other retainers’ homes along the slopes. At the foot of the mountain was a castle town protected by a sōgamae (outer defensive wall) and forts. Castle archaeology expert Yoshihiro Chida has noted that the scale and preservation of Nanao’s castle town ruins rival those of the Ichijōdani Asakura Clan Ruins in Fukui Prefecture.

Unlike many other castles, Nanao Castle avoided large-scale destruction or redevelopment because, after Maeda Toshiie relocated to Komaruyama Castle, urban development shifted there instead. As a result, many remains of the original structure have been preserved. The low stone walls of the main bailey (honmaru) are built in five tiers, and many of the stone walls of other enclosures still remain—an extremely rare feature among mountain castles. Alongside Kozeyama Castle in Wakasa, it is regarded as one of the most important surviving mountain castle sites and was designated a National Historic Site in 1934.

In 2005, ground-penetrating radar surveys revealed traces of building foundations such as pillar bases. It is said that one of the castle gates was relocated to Saikōji Temple in the city for preservation. In recent years, the Nanao City Board of Education has been maintaining the castle’s surroundings by trimming and clearing trees, allowing visitors to enjoy sweeping views of Nanao City, Nanao Bay, Notojima Island, and the Noto Peninsula.