During a port tour on April 9, 2025, images taken at a Japanese naval base, showed 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).
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.
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.
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.