Oyashio-class

The Oyashio class is a series of diesel-electric attack submarines operated by the Japan Maritime Self-Defense Force. Constructed by Kawasaki Shipbuilding Corporation and Mitsubishi Heavy Industries between 1994 and 2008, the class succeeded the Harushio class and preceded the Sōryū class. Eleven vessels were completed in total.

The design is larger than the preceding Harushio class to accommodate flank sonar arrays. The sensor suite includes hull-mounted sonar, flank arrays, a towed array, and an I-band search radar. Seven vessels received refits during their second and third maintenance cycles to extend their service lives and update systems to a standard similar to the Sōryū class.

The class entered commission in 1998. Service history includes participation in the Rim of the Pacific (RIMPAC) exercises in 2008 and 2010, alongside annual training exercises and port calls at Joint Base Pearl Harbor–Hickam and Maizuru Naval Base. The vessels Oyashio, Michishio, Makishio, and Isoshio were converted from attack submarines to training platforms. Several units utilize names previously assigned to World War II destroyers, while the Takashio name originates from a planned but unbuilt Yūgumo-class destroyer. Decommissioning of the earliest units in the class began in 2023.