The Japanese Navy replenishment program included the construction of two cruisers with fifteen 155 mm guns housed in triple-gun turrets and a displacement of 8,450 tons. The project was never implemented, but its further development led to the creation of the Tone-class heavy cruisers. An alternative development design involved arming the cruisers with dual-purpose 150 mm guns to create an anti-aircraft defense cruiser to combat American deck- and ground-based aviation.