- Type: Okinawan gusuku
- Other Names: Ôzato gusuku, Shimajiri Ôzato gusuku, Ufuzato gushiku
- Founder: Ufusato anji, 14th c.
- Status: Ruins
- Japanese: 南山城 (Nanzan gusuku)
Nanzan gusuku, also known as Shimajiri Ôzato gusuku, was an Okinawan gusuku-style fortress located in the Ôzato neighborhood of Itoman City, the ruins sit on a rise of Ryukyuan limestone roughly 60 meters above sea level. It is not to be confused, however, with Shimasoe Ôzato gusuku, which served as the chief center of power of the Nanzan kingdom.
Nozura-zumi (unshaped roughly assembled) stone walls remain today. The area around the castle is said to have once consisted of rugged hills, as well as a gentle slope and basin on the south side of the grounds, leading towards Kuniyoshi gusuku nearby. A ten-meter drop on the north side of the grounds led to a spring called Kadeshi-ga.
Legend has it that Taromai, last king of Nanzan, foolishly traded the Kadeshi-ga spring to Shô Hashi of Chûzan, for a gilded folding screen, an action which led to his downfall. Nanzan gusuku also features in the legend of Minamoto no Tametomo, a Japanese samurai who is said to have drifted or otherwise come to Okinawa in the 12th century, and to have sired Shunten, the first king of Okinawa. This legend is considered wholly apocryphal by most historians, who describe it as an obvious attempt at justifying Japanese connections to, or dominance over, the Ryukyuan royal family and by extension the entire kingdom. But, in any case, according to the legend, it was a daughter of Ufuzato anji, the lord of Nanzan, who married Tametomo and gave birth to Shunten.
As at many other gusuku, excavations have revealed a variety of goods, especially ceramics, including Sueki ware, Chinese and Korean celadons, and Tenmoku tea bowls, signs of vibrant trade connections in the 14th-15th centuries.
In 1915, the Takamine Elementary School was built on the castle grounds, reducing dramatically the extent of the remaining castle grounds. The remaining public area is known for its cherry blossoms, and a Shinto shrine located within the grounds.
- Kitahara Shûichi. A Journey to the Ryukyu Gusuku 琉球城紀行。 Naha: Miura Creative, 2003. p63.