However, by the time construction began, serious weaknesses in the Mogami-class hull design had become clear following the Fourth Fleet incident in 1935.

As Japan no longer was obligated to abide by the limitations of the London Naval Treaty, a new design was created and new means of construction were utilized.

Although the external dimensions were close to the Mogami class, the design was quite different, with all the main battery of guns placed forward of the bridge, reserving the entire stern area as a large seaplane operations deck.

[2] The Tone and the Chikuma were intended to provide the long range reconnaissance needed for Japan's carrier Air Fleets.

The Tone-class cruisers had a very distinctive silhouette, with all main armament concentrated forward and the aft section entirely devoted to aircraft operations.

When Japan abrogated the Washington Naval Treaty on 31 December 1936, the main armament was revised to eight 203 mm (8 in) guns in four twin turrets with maximum 55-degree elevation, as was installed on the Mogami-class vessels.

Tone (利根) was part of the covering force for the attack on Pearl Harbor, and later that same month assisted in the second Battle of Wake Island.

In February 1942, she was part of the covering force for the carrier raid on Darwin, and in March accompanied the battleships Hiei and Kirishima in the sinking of the destroyer USS Edsall.

During March Tone participated in the strike by Admiral Nagumo's aircraft carrier force into the Indian Ocean and the attack on Ceylon.

In October 1942, during the Battle of the Santa Cruz Islands, Chikuma was hit by five bombs dropped by aircraft from the carrier USS Hornet.