They were intended to reinforce Japan's "eight-eight fleet" of eight battleships and eight battlecruisers after the United States announced a major naval construction program in 1919.

However, having four large battleships and four battlecruisers on order put an enormous financial strain on Japan, which was spending about a third of its national budget on the Navy.

From an engineering aspect they were more than ten years ahead of their time because they anticipated the characteristics of the fully developed, fast battleship.

"[5] Naval architects William Garzke and Robert Dulin concur saying, "These ships would have completely outclassed any European battleship".

[6] The Number 13 class was designed by Captain Yuzuru Hiraga, the naval architect responsible for most of the previous Japanese capital ships.

The turbines were designed to produce a total of 150,000 shaft horsepower (110,000 kW), using steam provided by 22 Kampon oil-fired water-tube boilers, to reach a maximum speed of 30 knots (56 km/h; 35 mph).

[5] The waterline armor belt was intended have a maximum thickness of 330 millimeters (13 in) and, like the Kii class, it was angled 15° outwards at the top to increase its ability to resist penetration at short range.