The Taigei-class submarines (29SS), ( たいげい, 大鯨 ), Big Whale, is a new class of attack submarines developed for the Japan Maritime Self-Defense Force. It is the successor to the Sōryū class. The Taigei class is equipped with a large amount of lithium-ion batteries, as is the case with the eleventh and twelfth submarines of the Sōryū class (Ōryū and Tōryū), making it possible for the submersible to travel longer and at higher speeds under water than conventional diesel-electric submarines.

The development of the Taigei class were conducted from a variety of researches aimed at developing new and improved submarine components to improve the capabilities of next-generation submarines that will operate in the 2020s and beyond.