The Tosa-class battleships were two dreadnoughts ordered as part of the "Eight-Eight" fleet for the Imperial Japanese Navy (IJN) during the early 1920s. The ships were larger versions of the preceding Nagato class, and carried an additional 41-centimeter twin-gun turret. The design for the class served as a basis for the Amagi-class battlecruisers. The hull of the second ship, Kaga, was converted into an aircraft carrier of the same name.