Kawasaki Launches Sixth Taigei-Class Submarine with Lithium-Ion Batteries

Japanese shipbuilder Kawasaki Heavy Industries has launched the sixth Taigei-class submarine equipped with lithium-ion batteries.

The launch was announced on the official X account of the Japan Maritime Self-Defense Force (JMSDF).

The ceremony took place at Kawasaki’s Kobe shipyard, the birthplace of Japanese submarines. In keeping with Japanese tradition, the submarine’s name — Sogei (そうげい) — and pennant number 518 were revealed during the event.

The name translates as “bright big whale.” The submarine is scheduled to join the JMSDF in March 2027 to strengthen Japan’s submarine fleet.

Construction began on March 28, 2023. The submarine is fitted with lithium-ion batteries used as an air-independent power system, allowing extended underwater operations.

The Sogei has a standard displacement of 3,000 tons and a length of 84 meters, with a maximum submerged speed of 18 knots and 13 knots on the surface.

Its main armament includes six 533 mm torpedo tubes capable of launching Type 18 torpedoes and Harpoon anti-ship missiles. The boat will also be equipped with the new 12SSM-ER cruise missiles, recently introduced for both surface ships and submarines.

The Taigei-class was the first submarine type in the world specifically designed for lithium-ion battery use, marking a significant step in Japan’s submarine development.

In March 2025, the JMSDF commissioned the fourth Taigei-class submarine, the JS Raigei.

After the ceremony, Raigei departed for its home base in Kure, where it joined the 1st Group of the 1st Submarine Flotilla.

Unlike the first three boats in the class, Raigei features upgraded Kawasaki 12V2531 diesel engines with improved fuel efficiency and an enhanced ZQQ-8 sonar system produced by Oki Electric Industries.