Mitsubishi Heavy Industries (MHI) has marked a significant milestone in naval defense by launching the 12th and final Mogami-class frigate for the Japan Maritime Self-Defense Force (JMSDF) at its Nagasaki shipyard. The newly unveiled vessel, named JS Yoshii (FFM-12), honors the Yoshii River, which flows from the Mikuni Mountains in Okayama Prefecture into Kurashiki Bay.
This launch occurs a little over a year after Japan’s defense ministry granted MHI a contract worth approximately 58.3 billion yen ($371 million) to construct the final frigate. As reported by Naval News, the JS Yoshii is poised to enter its fitting-out phase following its launch, with plans for commissioning into the JMSDF by the fiscal year 2026, which concludes on March 31, 2027.
The Mogami-class program, initiated in 2019, aims to replace the aging Abukuma-class frigates currently utilized by the JMSDF. Notably, eight out of the twelve stealth surface combatants have already been commissioned, starting with the lead ship, JS Mogami (FFM-1), in April 2022. The subsequent frigates, numbered nine through eleven, have also been launched and are in the outfitting stages.
These vessels are approximately 133 meters (436 feet) long and displace around 3,900 to 4,000 metric tons. They operate with a crew of roughly 90 personnel and can achieve speeds of about 30 knots (56 kilometers or 35 miles per hour). Their armaments include a 127mm naval gun, surface-to-air and anti-ship missiles, anti-submarine rockets, torpedoes, and mine-laying capabilities.
As Japan concludes the initial batch of Mogami-class frigates, it is already advancing plans for an upgraded follow-on class. This new series, referred to as the “new FFM” or improved Mogami-class, will consist of another twelve vessels. The design enhancements include longer-range missiles, improved anti-submarine warfare capabilities, and a new ship-to-air guided missile system. These upgraded frigates will be larger than their predecessors, featuring a standard displacement of approximately 4,880 metric tons and an overall length of 142 meters (466 feet).
Construction for this next generation of frigates is planned at a rate of two ships per year at MHI’s Nagasaki and Tamano shipyards. The Maritime Systems subsidiary will also be involved in the production. In a notable development, the improved Mogami design was selected by Australia in August 2025 for its next-generation general-purpose frigate program, further underscoring the international interest in Japan’s naval advancements.
