Breaking News | Japan to test a new variant of electromagnetic railgun on JS Asuka experimental ship.

During a port tour on April 9, 2025, Twitter user モリジュン (Morijun) posted several images taken at a Japanese naval base, possibly Yokosuka, showing what appeared to be a new variant of a railgun installed on the Japan Maritime Self-Defense Force’s experimental ship JS Asuka (ASE-6102). The images depicted a turret with an angular design, consistent with prior official reports indicating that Asuka had hosted the first shipboard firing test of a railgun in 2023. This observation also aligns with ongoing test activities involving the electromagnetic weapon system developed by Japan’s Acquisition, Technology & Logistics Agency (ATLA).
Follow Army Recognition on Google News at this link

The images depicted a turret with an angular design, consistent with prior official reports indicating that the JS Asuka had hosted the first shipboard firing test of a railgun in 2023. (Picture source: Twitter/モリジュン)

JS Asuka is a one-of-a-kind experimental vessel that serves exclusively as a test platform for future equipment of the Japan Maritime Self-Defense Force (JMSDF). Built by Sumitomo Heavy Industries and launched in 1994, the ship was commissioned in March 1995. It was developed under the 1992 defense budget as the first purpose-built test ship for the JMSDF in fifteen years. It was named in accordance with JMSDF conventions for test ships, taking its name from Asuka, a historical site associated with Japan's cultural heritage. The ship is based at Yokosuka and is currently operated by the Development Squadron, now known as the Technology Evaluation and Development Unit. The construction cost was approximately 27.839 billion yen.

The ship is 151 meters long, 17.3 meters wide, and has a full-load displacement of 6,200 tons. It originally employed a COGLAG (combined gas turbine electric and gas turbine) propulsion system using LM2500 gas turbines for both electric generation and direct drive, though only two gas turbines remain in use following the removal of the electric-generation turbine. The propulsion system yields 43,000 PS and allows a top speed of 27 knots. The vessel carries a core crew of 72, plus accommodation for 100 test personnel. The layout includes dedicated quarters for both regular and test personnel, a multipurpose hall for briefings, and a medical facility with separate spaces for male and female crew members. Asuka was also the first JMSDF ship to embark female enlisted personnel.

The design of the ship includes a sharply protruding bow, adjusted to avoid interference with the ship's OQS-XX sonar system. This sonar consists of a bow dome cylindrical array and a single-side flank array due to budget limitations. The bridge superstructure includes four levels, with space reserved for radar testing. It previously hosted an early prototype of the FCS-3 radar system, featuring four AESA antennas. After tests concluded, parts of this prototype were repurposed for the Hyūga-class destroyers. As of fiscal year 2014, a prototype of the enhanced FCS-3 multifunction radar using the X-band was mounted on the vessel.

Built by Sumitomo Heavy Industries and launched in 1994, the JS Asuka (ASE-6102) is a one-of-a-kind experimental vessel that serves exclusively as a test platform for future equipment of the Japan Maritime Self-Defense Force. (Picture source: Twitter/モリジュン)

The deck forward of the bridge at the 01 level initially had a three-deck-high compartment that later housed an eight-cell Mk.41 mod.17 Vertical Launch System (VLS) for testing the future 07 VLA and the A-SAM (later designated as the Type 23 ship-to-air missile). This VLS was removed during maintenance at the end of fiscal year 2022. Additional test installations included a fixed acoustic jammer (FAJ) and a mobile decoy (MOD) as part of a torpedo defense system. The ship also tested torpedo launch systems updated for the Type 12 torpedo, although these were no longer in use as of 2023.

The aft main deck serves as a helipad for H-60 series helicopters, with a hangar capable of housing the SH-60J. The space is officially designated as a "development equipment warehouse" and is also used to store test equipment or serve as a waiting area during adverse weather. The work deck below includes equipment for towed sonar testing. In 2019, modifications were made to the rear deck to support tests of VDS+TASS sonar systems used on the Mogami-class frigates. In December 2022, JS Asuka participated in the live-fire test of the new A-SAM, later designated as the Type 23 ship-to-air missile.

Throughout its nearly three-decade-long service, JS Asuka has been outfitted with and has tested an extensive range of sensors, weapons, propulsion systems, and integrated combat technologies. Between 1995 and 1998, it supported tests of the OQQ-XX sonar, COGLAG propulsion, and the FCS-3 system. It also tested infrared detection equipment in 1998 and the new OYQ-10 tactical information processing system from 1999 to 2000. It became part of the newly formed Development Squadron in 2002 after the reorganization of its predecessor. Trials for the Type 07 VLA system occurred from 2003 to 2007, while testing for the Type 12 torpedo spanned from 2007 to 2011. It participated as a simulated suspect vessel in PSI maritime training exercises in October 2007. During the 2011 Tōhoku earthquake and tsunami, Asuka departed 53 minutes after the quake for disaster response operations and continued until April 8.

By 2016, the Japanese government had launched the full-scale development of a 40mm railgun system intended to explore high-velocity electromagnetic acceleration for future air defense and surface strike applications. (Picture source: Twitter/モリジュン)

In subsequent years, Asuka contributed to the testing of underwater self-propelled targets (2012), radars for the Asahi-class (2014), MQ-8C compatibility (2015), and the Type 12 surface-to-ship missile’s shipboard integration (2017), as well as the validation of the COGLAG propulsion system—an early Japanese experiment combining gas turbine and electric drive components, which laid the groundwork for propulsion systems on other JMSDF vessels. In 2020, administrative control of the ship was transferred to a newly established unit, and in 2023, it was reassigned to the JMSDF’s Technology Evaluation and Development Unit following another organizational restructuring.

One of the most recent and prominent trials involving Asuka was the shipboard railgun test—one of the most ambitious developments undertaken on the experimental ship. Japan’s Ministry of Defense began foundational research into electromagnetic projectile acceleration technologies in the mid-2010s, following early small-caliber trials with a 16mm prototype. By 2016, the Japanese government had launched the full-scale development of a 40mm railgun system intended to explore high-velocity electromagnetic acceleration for future air defense and surface strike applications, while withstanding repeated firing without significant degradation of the barrel. Significant engineering advances were made between 2016 and 2022, including a successful 120-shot durability test in which a projectile was consistently accelerated to speeds exceeding 2,000 meters per second.

In October 2023, ATLA announced it had conducted the world’s first successful railgun firing test at sea, in cooperation with the JMSDF. The test was supported by JS Asuka, which was specially adapted to host the test equipment, including a 6-meter-long, 8-ton railgun and associated power supply systems comprising one 20-foot container for charging and three containers housing a capacitor bank with 5 MJ of capacity. Projectiles fired included a simplified integrated round and a more complex two-part armor-piercing round, each weighing approximately 320 grams and measuring about 160 mm in length. A press release dated November 1, 2023, and images from the test showed a railgun setup with extensive cable connections installed aboard the ship. On October 19, JMSDF Commander Vice Admiral Akira Saitō visited ATLA’s Shimokita Test Site to inspect the railgun development status.

Japan aims to achieve prototype readiness for a small-caliber ship-based railgun system for anti-ship applications by 2027. (Picture source: Twitter/モリジュン)

In parallel with domestic development, Japan has pursued international cooperation. One engineer from ATLA was seconded to a U.S. Navy research institution from January 2023 to June 2024, where they reviewed facilities and interviewed researchers involved in electromagnetic weapon development. On May 30, 2024, Japan’s Ministry of Defense signed an implementation arrangement with the French and German defense ministries and the joint French-German Saint-Louis Research Institute to facilitate information exchange and assess the potential for joint development of railgun technologies.

The railgun project in Japan is part of a broader initiative to develop long-range, high-speed intercept capabilities against hypersonic and other advanced threats. Future objectives include miniaturization of the power supply system, with plans to reduce charger volume by 50% within five years and capacitor volume by 90% over a ten-year timeframe. According to the Ministry of Defense's 2022 plan, Japan aims to achieve prototype readiness for a small-caliber ship-based railgun system for anti-ship applications by 2027, and a medium-caliber air-defense version suitable for ship, ground, or vehicle deployment by 2028.