On December 22, Japanese shipbuilder Mitsubishi Heavy Industries (MHI) launched the 12th and final Mogami-class multirole frigate for the Japan Maritime Self-Defense Force (JMSDF).
The 133-meter-long vessel, named Yoshii (pennant number FFM-12), was launched during a naming and launching ceremony held at MHI’s Nagasaki Shipyard & Machinery Works in Nagasaki Prefecture.
The ship is named after the Yoshii River (吉井川), a first-class river flowing through eastern Okayama Prefecture in western Japan. This is the first time the JMSDF has assigned the name Yoshii to a warship, and the name has no precedent in the former Imperial Japanese Navy.
Following the launch, JS Yoshii will enter the fitting-out phase ahead of delivery and commissioning, which the JMSDF expects to take place by the end of fiscal year 2026, ending on March 31, 2027.
JS Yoshii is being built for about 58.3 billion yen ($371 million) under a contract awarded in February 2024, according to Mitsubishi Heavy Industries and the Ministry of Defense.
High-Tempo Construction Program
Japan is accelerating the procurement of compact, missile-equipped multi-mission frigates to bolster deterrence against China and Russia in the East China Sea, the Sea of Japan, and the wider Indo-Pacific.
The Mogami-class program has advanced at an unusually rapid pace, with two ships budgeted and built per year since fiscal year 2018. Eight of a planned fleet of 12 Mogami-class frigates have already entered service. All vessels are scheduled to be commissioned by March 2027, completing the JMSDF’s first FFM production run.
Eight ships are already in service: Mogami, Kumano, Noshiro, Mikuma, Yahagi, Agano, Niyodo, and Yubetsu. All have been assigned to Escort Divisions with two-digit numbers directly under The Fleet Escort Force.
Specifically:
- Mogami and Kumano: Escort Division 11 (Yokosuka base)
- Noshiro and Mikuma: Escort Division 13 (Sasebo Base)
- Yahagi and Agano: Escort Division 14 (Maizuru Base)
- Niyodo: Escort Division 12 (Kure Base)
- Yubetsu: Escort Division 15 (Ominato)
These two-digit escort divisions primarily conduct operations in regional and coastal waters.
The 9th ship Natori, 10th ship Nagara, and 11th ship Tatsuta have already been launched and are currently undergoing outfitting.
All Mogami-class frigates assigned to Escort Divisions 11 through 15 are scheduled to be placed under the Patrol and Defense Group (provisional name), which will be subordinate to the newly established Fleet Surface Force(provisional name) to be formed by the end of March 2026. The JMSDF’s new Offshore Patrol Vessel (OPV) class, including lead ship Sakura and second ship Tachibana—launched on November 13—are also slated under the Patrol and Defense Group.
First JMSDF Escort Ship with Organic Mine Warfare Capability
The Mogami class has a standard displacement of 3,900 tons, a length of 133 meters, a beam of 16.3 meters, and a top speed of about 30 knots. The class represents the JMSDF’s latest generation of stealth surface combatants, featuring smooth hull and superstructure lines designed to reduce radar cross-section. Crew size has been reduced to around 90 personnel through extensive automation.
The class is distinguished by its multi-role capability and its organic mine warfare function—an unprecedented feature for JMSDF escort ships. In addition to peacetime surveillance and patrol missions, Mogami-class vessels are designed to conduct anti-submarine, anti-air, and anti-surface warfare during contingencies.
The designation “FFM” combines “FF” (frigate) with “M” for multi-purpose missions and mine warfare. Traditionally, mine countermeasures (MCM) have been the exclusive domain of dedicated minesweepers in the JMSDF. The Mogami class is the first escort ship class to incorporate MCM capabilities, a feature that remains rare among frigates in other navies as well.
All 12 ships are budgeted to receive vertical launch systems (VLS). From the 7th ship Niyodo onward, VLS has been installed at the time of commissioning; Earlier ships were commissioned in a “fitted for but not with” configuration. Each vessel is equipped with 16 cells of the Mk 41 VLS.
Follow-on Program: 12 Improved Mogami-class Vessels
Beginning with fiscal year 2024, the Ministry of Defense in Tokyo has started procuring the upgraded Mogami-class frigate—known in Tokyo as the “New FFM” and also called as the 06FFM—over a five-year period, totaling 12 new ships.
Compared with the original Mogami class, the new FFM design will feature enhanced air-defense and radar capabilities, bringing it closer in role and capability to a missile frigate (FFG). According to a senior JMSDF official interviewed by the author, the original Mogami class was developed under tight budgetary constraints, limiting the systems that could be installed. However, under the former Fumio Kishida administration’s policy of fundamentally strengthening defense capabilities, increased funding has allowed for a larger hull, expanded weapons fit, and a doubling of VLS cell numbers in the new design.
As illustrated in the program schedule above, the first and second improved FFM vessels are expected to enter service in fiscal year 2028. If construction proceeds smoothly, all 12 improved Mogami-class frigates will be commissioned by fiscal year 2032. Combined with the original Mogami class, the JMSDF would operate a total of 24 FFM-series ships by that time.
Japan to Transfer “Unicorn” Integrated Antenna System to India
On November 15, 2024, Japan’s Acquisition, Technology & Logistics Agency (ATLA) signed a memorandum of intent with India to transfer the “Unicorn” integrated stealth antenna system installed on the Mogami-class frigates.
If realized, this would mark Japan’s first export of defense equipment to India under the bilateral defense equipment and technology transfer agreement signed in December 2015. It would also represent Japan’s second overseas transfer of a complete defense system, following the export of air surveillance radars to the Philippines.
The FFM is equipped with a wide variety of weapons and systems as listed below:
BAE Systems 5-inch (127-mm) 62-caliber Mk 45 Mod 4 naval gun system ×1
Japan Steel Works 12.7mm Remote Weapon System ×2
Mk.41 VLS (16 cells)
Raytheon SeaRAM ×1
MHI Type 17 surface-to-ship guided missile (SSM-2) 4-tube launcher x 2
Mitsubishi Electric OPY-2 multifunction Radar
Mitsubishi Electric OAX-3EO/IR sensors
Hitachi OQQ-11 anti-mine sonar
NEC OQQ-25 anti-submarine sonar (VDS/TASS)
UUV (OZZ-5 by MHI) and USV (by JMU Defense Systems) for mine countermeasures
Sea mines for offensive mine warfare
In an epoch-making move, in August, the Australian government selected the upgraded Mogami-class frigate as the Royal Australian Navy’s next-generation general-purpose frigate.
