Japan has effectively completed one major segment of its surface fleet recapitalization with the Dec. 22, 2025 launch of the 12th Mogami-class multirole frigate, JS Yoshii, by Mitsubishi Heavy Industries. 

Delivery of the final ship is scheduled for FY2026, marking the end of a tightly paced 12-ship program that emphasized automation, reduced crew size, and serial production discipline. 

The milestone is less an endpoint than a hinge: Japan is already transitioning to an upgraded “New FFM” design, also planned at 12 hulls, with first units expected around FY2028 and a broader in-service presence forming in the early 2030s.

“Stacked” Modernization, Not Isolated Programs

The Mogami milestone sits inside a wider, simultaneous naval modernization effort. 

Rather than sequential ship classes, Japan is refreshing surface combatants, undersea forces, air and missile defense, and long-range strike capacity in parallel, supported by multi-year spending increases introduced after 2022. 

This approach has compressed timelines and raised industrial tempo, keeping production lines active while new capabilities are introduced incrementally rather than deferred to a single future class.

Missile Defense and Aviation at Sea

A central pillar is sea-based air and missile defense. 

Japan is building two Aegis System Equipped Vessels (ASEV) following the cancellation of the Aegis Ashore plan. 

Commissioning timelines vary by source, ranging from JFY2027–2028 in industry statements to March 2028 and March 2029 in trade reporting, but the program is funded and under construction. 

In parallel, the Japan Maritime Self-Defense Force is advancing “carrier-like” aviation through the conversion of Izumo-class helicopter destroyers. 

JS Kaga has conducted multiple F-35B flight operations with allied aircraft, while Japan’s aviation plans commonly cite 42 F-35Bs within a larger F-35 procurement.

Undersea and Standoff Strike Emphasis

Undersea modernization continues on an annual rhythm. 

The sixth Taigei-class submarine, JS Sogei (SS-518), was launched on Oct. 14, 2025, sustaining a production cadence tied to incremental propulsion and quieting upgrades. 

At the same time, Japan is integrating longer-range strike systems. 

Contracts cover up to 400 Tomahawk cruise missiles—200 Block IV and 200 Block V—while upgraded Type 12 missiles, described at roughly 1,000 km range, are being accelerated for initial deployment by March 2026 at one site.

Experimentation Alongside Fleet Growth

Japan is also testing lower-cost defenses against drones and saturation threats. 

In December 2025, a containerized high-energy laser prototype was installed on test ship JS Asuka as part of an acquisition agency-led directed-energy program. 

Together with frigate automation, expanded vertical launch capacity, and export-relevant production scale—highlighted by Australia’s selection of an upgraded Mogami design—the effort reflects a doctrine focused on deterrence by denial, sustained presence, and survivability in a missile-dense environment.