MHI Showcases Advanced Mogami Frigate, UUV at DSEI Japan

Mitsubishi Heavy Industries (MHI) is highlighting its growing portfolio of advanced defence technologies at this year’s DSEI Japan exhibition, with a focus on next-generation platforms and modular systems that reflect evolving operational concepts within and beyond the Japan Self-Defense Forces (JSDF). Among the highlights are an upgraded Mogami-class frigate, a newly developed long-endurance Unmanned Underwater Vehicle (UUV), and the multi-domain CoasTitan unmanned system.

One of the centrepieces of MHI’s unmanned technology showcase is CoasTitan, a flexible and modular unmanned system architecture. Rather than a single system, CoasTitan is a concept that integrates Unmanned Aerial Vehicles (UAVs), Unmanned Surface Vehicles (USVs), and Unmanned Underwater Vehicles (UUVs) under a unified control framework. The design is highly scalable and mission-adaptable, intended to support diverse operational requirements across air, surface, and subsurface domains.

According to MHI, CoasTitan is engineered to support both autonomous and semi-autonomous operations, and its open-architecture design ensures compatibility with existing command and control systems used by the JSDF and potential international partners. The system is currently deployable and is undergoing continuous enhancement through incremental upgrades to both its hardware interfaces and mission software. This reflects Japan’s strategic interest in distributed maritime operations and autonomous technologies that can reduce the risk to human personnel while increasing operational resilience.

In parallel with its unmanned developments, MHI is showcasing a scale model of the latest variant of the Mogami-class frigate. This updated version marks a notable shift in the platform’s size and capability. The new hull measures 142 metres in length—up from 133 metres in the original design—and the beam has been expanded from 16.3 metres to approximately 17 metres. These physical changes accommodate a range of system enhancements, most notably in anti-air warfare capability and multi-role mission support.

The revised configuration reinforces the ship’s adaptability. It has been optimised for extended-range operations and incorporates improved radar and sensor suites. It also features the ability to deploy and recover USVs from the ship’s stern ramp or well deck, with control and monitoring functions integrated into the ship’s bridge systems. These features make the FMF a versatile platform suited for tasks ranging from maritime security and patrols to mine countermeasure (MCM) missions and area denial operations.

The expanded mine warfare functionality is particularly notable, reflecting Japan’s renewed emphasis on sea lane protection and strategic deterrence in surrounding waters. The ability to launch USVs and remotely operated systems enhances the vessel’s operational reach and reduces risk in contested environments.

Also presented at the exhibition is MHI’s latest long-endurance Unmanned Underwater Vehicle (UUV), developed for sustained underwater operations. First conceptualised in 2019, the system reached its baseline configuration by 2022 and is currently undergoing extensive sea trials. In its standard form, the UUV measures 10 metres in length, but can be extended to 16 metres through modular additions.

Internally, the UUV is designed with separate compartments for propulsion, power storage, and payload modules, allowing it to be reconfigured for surveillance, mine detection, or research roles. The lithium-ion battery system provides multi-day operational endurance, and MHI is actively exploring wireless underwater charging to increase mission duration further. A range of autonomous navigation technologies, including acoustic sonars and optical imaging systems, allows the UUV to perform its missions with minimal surface communication.

While MHI has not disclosed the vehicle’s maximum operating depth, it has indicated that its development draws upon the company’s extensive experience in submarine and underwater vehicle design. The system’s endurance, scale, and modularity are aimed at enhancing Japan’s capacity for persistent undersea surveillance and long-range reconnaissance, particularly in the Pacific’s increasingly contested maritime zones.

Overall, MHI’s display at DSEI Japan reflects a broader trend towards multi-domain integration, autonomy, and flexible mission architecture in modern defence procurement. The company’s efforts are aligned with Japan’s national defence strategy, which places growing emphasis on unmanned technologies and resilient force structures suited for island defence and rapid response.