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The Japan Maritime Self-Defense Force commissioned the JS Chōgei (SS 517) on March 10, 2026, marking its fifth Taigei-class submarine. The vessel, measuring 84 meters and displacing 3,000 tonnes, will enter operational service in March 2026 and is part of a planned fleet renewal comprising eight submarines.

Constructed at Mitsubishi Heavy Industries with a budget of 64.8 billion yen, it features advanced propulsion systems, improved sonar capabilities, and lithium-ion battery technology. The JS Chōgei is assigned to Yokosuka Naval Base and incorporates design modifications for mixed-gender crews, reflecting personnel policy changes in Japan's defense forces.