Kawasaki Heavy Industries officially launched the sixth Japanese submarine of the class Taggeii at a ceremony in Kobe. This new ship, named JS Sogei (SS 518)carrying the latest generation lithium ion battery technology.
The ceremony took place at the Kawasaki shipyard in Kobe — a city known as the birthplace of Japanese submarine building — and was attended by naval officials as well as representatives of the Japan Maritime Self-Defense Force (JMSDF).
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The name “Sogei” (そうげい) means “large and radiant whale,” following class tradition Taggeii who named his submarine after a term related to the sea and whales.
According to JMSDF, JS Sogei will officially join the Japanese fleet in March 2027, strengthening the country’s undersea capabilities amid growing fleet modernization in the Indo-Pacific region.
Construction of Sogei began on March 28, 2023. The submarine is designed to operate using a lithium-ion battery-based propulsion system — a technology that replaces conventional free-air (AIP) systems — allowing for longer underwater range, lower noise levels and simpler maintenance.
With a standard displacement of 3,000 tons and a length of 84 meters, JS Sogei can reach speeds of up to 18 knots when submerged and 13 knots on the surface. Its main armament consists of six 533 mm torpedo tubes compatible with Type 18 torpedoes and Harpoon anti-ship missiles.
This submarine will also be equipped with new cruise missiles 12ssm-iswhich was recently introduced to expand the attack range of the Japanese Navy.
Class Taggeii representing a technological milestone for Japan, being the first in the world developed specifically to operate on lithium ion batteries. This innovation places the Japanese fleet among the most advanced in the world in terms of silent propulsion and energy efficiency.
In March 2025, the JMSDF has added a fourth submarine of the same class, JS Raigeiwhich is currently based in Kure. Unlike the initial model, the Raigei is equipped with an updated Kawasaki 12V2531 diesel engine and a modern ZQQ-8 sonar system from Oki Electric Industries, demonstrating the continued evolution of this class.
Source and images: Japanese Ministry of Defense – Maritime Self-Defense Force | @JMSDF_PAO_. This content was created with the help of AI and has been reviewed by the editorial team.
