How Japan is engineering the next generation of silent, high-speed attack submarines

Wars & Conflicts · Published 9 October 2026 Swipe more like this →

In short: The Taigei-class represents a major leap in undersea warfare. By utilizing advanced lithium-ion batteries, these submarines can travel faster and longer underwater than conventional diesel-electric models, fundamentally changing how the Japan Maritime Self-Defense Force monitors complex marine environments.

Created to follow the Sōryū class, the Taigei-class aims to satisfy 2020s-era technological requirements. A defining feature of this class is its extensive use of lithium-ion batteries, a technology previously explored in the eleventh and twelfth Sōryū-class submarines, the Ōryū and Tōryū. This shift allows for significantly enhanced underwater speed and endurance compared to traditional diesel-electric propulsion.

The development process was a massive, multi-year undertaking involving intense research into stealth and survivability. Between 2004 and 2009, researchers spent 800 million yen on simulations and in-house testing to optimize design and cost-effectiveness. Other critical research areas included anti-detection structures, such as a proposed floating floor design intended to dampen vibrations and mitigate external shocks. A prototype for this buffering mechanism was developed between 2007 and 2011 and tested through 2014, with 400 million yen allocated to the project.

To maintain a competitive edge, the Japan Maritime Self-Defense Force has invested heavily in sonar and power systems. For instance, research into a new sonar system to counter the increasing quietness of foreign vessels in the 2030s involved 5.1 billion yen. Additionally, the first submarine of the class, the Taigei, was converted into a dedicated test submarine in 2024. This strategic move allows for accelerated research and development without pulling frontline combat vessels from active service, thereby increasing overall monitoring capabilities.

These vessels are armed with the Type 18 torpedo, which succeeds the older Type 89 model.

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