The Shikishima (PLH 31) is the largest patrol vessel of the Japan Coast Guard

Japan Coast Guard

The , formerly the Maritime Safety Agency, is the Japanese coast guard. Comprising about 12,000 personnel, it is under the oversight of the Ministry of Land, Infrastructure, Transport and Tourism, and is responsible for the protection the coast-lines of Japan...

. She was built by Ishikawajima-Harima Heavy Industries

Ishikawajima-Harima Heavy Industries

, formerly known as , is a Japanese company which produces ships, aero-engines, turbochargers for automobiles, industrial machines, power station boilers and other facilities, suspension bridges and other transport-related machinery....

 Tokyo.

Planned to guard plutonium

Plutonium

Plutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation...

 transport ships, the Shikishima is the largest and heaviest-equipped patrol vessel of the JCG. With her cruising capacity, she can make voyages from Japan to Europe without making any calls.

She is the only JCG ship equipped with anti-air radar and Oerlikon 35 mm twin cannon

Oerlikon 35 mm twin cannon

The Oerlikon 35 mm twin cannon is a towed anti-aircraft gun made by Oerlikon Contraves . The system was originally designated as 2 ZLA/353 ML but this was later changed to GDF-001...

s, so she has increased anti-air firepower. Usually, PL (Patrol vessels, Large) have only a navigation radar and a single-mounted 35mm or 40mm autocanon. And the JM61 20mm Vulcan

M61 Vulcan

The M61 Vulcan is a hydraulically or pneumatically driven, six-barreled, air-cooled, electrically fired Gatling-style rotary cannon which fires 20 mm rounds at an extremely high rate. The M61 and its derivatives have been the principal cannon armament of United States military fixed-wing aircraft...

 on the single-mounted Remote weapon system later became a model for the 20mm RFS (Remote Firing System), which is on modern PMs and PSs such as the Tsurugi class PS

Tsurugi class patrol vessel

The Tsurugi class （） is a class of small patrol vessel of the Japan Coast Guard . The development of this class was one of the earliest attempts of the JCG to deal with spy boats from North Korea...

. The OPS-14 2D air search radar is the Japanese counterpart of the American AN/SPS-49

AN/SPS-49

The AN/SPS-49 is a United States Navy two-dimensional, long range air search radar built by Raytheon that can provide contact bearing and range. It is a primary air-search radar for numerous ships in the U.S...

.

At present, she is frequently sent on long cruises to Southeast Asia

Southeast Asia

Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...

 to foster international cooperation against piracy in the Strait of Malacca

Piracy in the Strait of Malacca

Piracy in the Strait of Malacca has historically been an unresolved threat to ship owners and the mariners who ply the 900 km-long sea lane...

. She is also assigned to the policing mission of Senkaku Islands

Senkaku Islands

The , also known as the Diaoyu Islands or Diaoyutai Islands or the Pinnacle Islands, are a group of disputed uninhabited islands in the East China Sea...

because of her cruising capacity. The JCG appreciate her capability, so they have been planning to build two more vessels based on this design