Maruoka Domain Battery, Coastal artillery fortification in Mikuni, Japan

Maruoka Domain Battery is a coastal artillery fortification built with a bow-shaped earthen rampart reinforced by stone. The structure sits on an elevated plateau and features five openings designed for cannon placement.

The battery was built in 1852 by the Maruoka Domain to respond to growing Western naval activity off the Japanese coast. Its construction marked a turning point when traditional domains adopted modern artillery defenses.

The site is also called Kaji Daiba after Kaji Bay, where it stands. Maruoka Domain's gunnery expert Kurihara Genzaimon, a student of Takashima Shuhan's Western-style artillery, directed its construction. In 1866 the domain reorganized its samurai into a Western-style rifle-armed force.

The site is easy to reach but sits on elevated terrain that requires time to explore fully. The surroundings offer good views of the coast and panoramas over the water.

The battery was completed in February 1852, a year before Perry's fleet reached Uraga. Maruoka Domain planned several more batteries, but its finances did not allow construction, so this rampart on a 30-metre plateau above the sea remained the domain's main coastal work.