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.

Sakai is a city located in Fukui Prefecture, Japan. As of 10 May 2018, the city had an estimated population of 92,210 in 31,509 households and a population density of 550 persons per km2. The total area of the city was 209.67 square kilometres (80.95 sq mi).