The armament of the scout cruisers originally included six 140 mm twin-gun turrets, but the project was later revised. In the 1930s, the Furutaka-class cruisers were rebuilt following the pattern of the Aoba-class cruisers and received three twin-gun turrets. If this hadn't happened, such cruisers would most likely have been turned into anti-aircraft defense ships during World War II with 127 mm dual-purpose guns in twin-gun mounts.