|Address||(Honmaru Main Tower) Ninocho, Nakatsu City, Oita Prefecture|
|Contact||Nakatsu Castle (Okudaira Clan Historical Museum)|
Nakatsu Castle was built by feudal lord Kuroda Kanbei, an adviser to Toyotomi Hideyoshi, as a part of the late shogun's plan to unify Kyushu and the rest of the country. The shape of the castle resembled a folding fan, and it was often referred as "Ougi Castle."
Nakatsu Castle is one of the three water fortified castles in the country. It drew salt water from the nearby sea to fill the moat around the fortification.