The ships of this class displaced 11,633 tons (standard), were 201 metres (659 ft) long, and were capable of steaming at 36 knots (67 km/h; 41 mph).

Following innovations pioneered in Yubari, the armor belt was made an integral part of the hull structure to reduce weight.

[2] As originally constructed, the class was armed with a main battery of ten 200 mm (7.9 in) 20 cm/50 3rd Year Type 1 GÔ naval guns mounted in 5 twin turrets, the heaviest armament of any heavy cruiser in the world at the time.

[3] Torpedo armament was unusually heavy compared to the cruisers of other nations at the time, with 12 carried in fixed single launchers inside the hull.

[3] The second modernization in 1939 added an additional two quadruple torpedo launchers and enhanced light anti-aircraft armament with the introduction of the Type 96 25mm gun.

Almost immediately afterwards, Haguro fired a spread of torpedoes, one of which hit the destroyer Kortenaer which blew in half and sank nearly instantly.

A torpedo from Nachi hit the light cruiser Java, which ignited her amidships magazines and blew her in two and sank her in under two minutes.

Four minutes later, a torpedo from Haguro hit the aforementioned light cruiser De Ruyter, sinking her over three hours and killing Admiral Karel Doorman.

Subsequent gunfire hits disabled Exeter's remaining boilers, engine, guns, and electrical power and lit her aflame, leading to her screw scuttling her.

Haguro and Nachi were almost entirely out of ammo and retreated, while Myōkō and Ashigara combined fire to sink the destroyer HMS Encounter.

The destroyer USS Pope initially escaped but was crippled by planes from the light carrier Ryūjō and later finished off by Myōkō and Ashigara.