The B-64/B-65 (depending on the source) class were to be battlecruisers that were similar in appearance to the Yamato class but with 12.2" guns.
Initial design work started in the 1939 / autumn of 1940. In 1941 it was decided to mount 14.2" guns in three twin turrets after the armament of the Alaska class became known.
Two ships were ordered under the 1942 Fifth Replenishment Program but the programme was cancelled.
There were to be three aircraft that would have had a catapult just aft of the funnel. A crane would be used to lift them back on board.
The first of the 12.2" guns was tested in 1941.