According to the 1922 Washington Naval Treaty articles, Japan was permitted to begin new construction to replace its WWI vintage battle-fleet, with the two oldest classes being considered for replacement: the Kongo-class battlecruisers, and the Fuso-class battleships. Designed by Yuzuru Hiraga just as the 1930 London Naval Treaty discussions were about to begin, the replacements for the Kongos would resemble the Yamato and her preliminary designs, featuring good speed, a displacement between 30,000 - 35,000 tonnes, and a main armament of 41 cm guns.

Multiple variants were proposed by Hiraga, but the final design that was held up for consideration had the following characteristics:

General characteristics (as designed)
Displacement:	35,000 t 39,200 t (full load)
Length:	232 m (761 ft 2 in) (overall)
Beam:	32 m (104 ft)
Draft:	9 m (29ft 6 in)
Installed power:	160,000 shp
Propulsion:	4 shafts; 4 steam turbines
Speed:	26.5 knots (49 km/h)
Armament:	9 × 41 cm guns (2x2 + 2x3) 16 × 15.2 cm guns (4x2 + 8x1) 8 × 12 cm guns (4x2) 2 x 61cm torpedo tubes
Aircraft carried:	2 Seaplanes
Aviation facilities:	1 catapults