Japan has added a new stealth asset to its underwater fleet, with the Japan Maritime Self-Defense Force formally receiving its fifth Taigei-class submarine on March 10.
The vessel, named JS Chōgei, was handed over by Mitsubishi Heavy Industries at its Kobe shipyard. The induction comes amid intensifying regional naval competition in the western Pacific.
Delivery and deployment plans
The newly delivered submarine was constructed over a three-year timeline. Work began in 2022, followed by its launch in 2024, before final delivery this year. After commissioning, the submarine was assigned to Submarine Division 2 under Submarine Flotilla 2.
Its homeport will be the Yokosuka Naval Base in Kanagawa Prefecture. From there, it will conduct anti-surface and anti-submarine warfare missions along with intelligence, surveillance, and reconnaissance operations.
The submarine is also expected to patrol strategic sea lanes, especially the Miyako Strait. This narrow passage is a key maritime chokepoint linking the East China Sea and the Pacific Ocean, making it vital for regional security monitoring.
Design evolution and program background
The Taigei-class program traces its roots back to 2004, when Japan began planning a successor to its Soryu-class submarines, which entered service in 2009. Construction of the new class began in 2012, with a focus on improved stealth and detection capabilities.
Compared to earlier submarines, the Taigei class features slightly larger dimensions and upgraded internal systems. The JS Chōgei measures about 275 feet in length, with a beam of nearly 30 feet and a draft of around 34 feet. It displaces approximately 3,307 US tons and can accommodate about 70 crew members.
A notable addition is a dedicated accommodation space for female personnel, reflecting gradual modernization in crew integration within the fleet.
The submarine’s name, “Chōgei,” translates to “long whale,” continuing a naming tradition where vessels in this class include the word “whale,” symbolizing size and stealth.
Advanced propulsion and onboard systems
The Taigei-class submarines are powered by a diesel-electric propulsion system generating roughly 6,000 horsepower. They use lithium-ion batteries instead of traditional lead-acid systems, allowing longer underwater endurance and improved operational efficiency.
JS Chōgei is equipped with advanced sonar technology, including the ZQQ-8 sonar suite, which enhances detection capability over earlier systems. It also features a modern combat management system that integrates sensors, command functions, and weapon control.
The submarine incorporates a redesigned snorkel system to improve battery charging efficiency while reducing its detectable signature. In addition, it uses non-penetrating optronic masts instead of traditional periscopes, further enhancing stealth and situational awareness.
Weapons and strategic role
The Taigei-class submarines are armed with heavyweight torpedoes and anti-ship missiles, including the UGM-84L Harpoon Block II, which has a range of about 154 miles. These capabilities allow the submarine to engage both underwater and surface threats.
Reports suggest the platform may also be capable of deploying future hypersonic weapons, such as a Hyper Velocity Gliding Projectile, though this remains under development.
Japan plans to build a total of 10 Taigei-class submarines by 2031. The program is progressing steadily, with additional units already under construction.
The growing fleet is expected to play a critical role in monitoring increased naval activity in the region. As neighboring countries expand their maritime capabilities, Japan’s submarines are seen as a key deterrent force, often described as quiet but highly effective assets beneath the surface.