Maruoka Castle is a Japanese castle, located in Maruoka, Fukui, and famous for its donjon (tenshu), the oldest in Japan. Built in 1576 by order of Shibata Katsutoyo, only the central tower (tenshu) remains; the grounds are used by the local populace for festivals such as hanami and traditional parades. The castle is also known as Kasumi-ga-jō due to the legend that whenever an enemy approaches the castle, a thick mist appears and hides it.