Maruoka Castle is a hirayama-style Japanese castle located in the Maruoka neighbourhood of the city of Sakai, Fukui Prefecture, in the Hokuriku region of Japan. It also called Kasumi-ga-jō due to the legend that whenever an enemy approaches the castle, a thick mist appears and hides it. Built at the end of the Sengoku period, the castle was occupied by a succession of daimyō of Maruoka Domain under the Edo period Tokugawa shogunate. The site is now a public park noted for its sakura. The castle's relatively small tenshu claims to be the oldest in the country, a claim which is challenged by both Inuyama Castle and Matsumoto Castle.

Fukui Prefecture is a prefecture of Japan located in the Chūbu region of Honshū. Fukui Prefecture has a population of 778,943 and has a geographic area of 4,190 km2. Fukui Prefecture borders Ishikawa Prefecture to the north, Gifu Prefecture to the east, Shiga Prefecture to the south, and Kyoto Prefecture to the southwest.