Tone - class cruiser The two were the last heavy cruiser s completed for the Imperial Japanese Navy . The " Tone " - class cruisers were originally envisaged as the 5th and 6th vessels in the " Mogami " - class . 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 . Though 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 hangar . Unlike the U . S . Navy , the Japanese did not have a dual role attack / scout aircraft , nor did they assign any of their carrier aircraft to a reconnaissance role . Little emphasis was placed on this aspect of carrier warfare . Instead the Japanese reserved all of their carrier aircraft for attack roles . Reconnaissance then was relegated to the float planes carried by cruisers . The " Tone " and the " Chikuma " were intended to provide the long range reconnaissance needed for Japan ' s carrier Air Fleets . Design . Overview . The " Tone " - class cruisers had a very distinctive silhouette , with all main armament concentrated forward and the aft section entirely devoted to aircraft operations . This allowed for strong and compact protection of the magazines while also increasing and improving the living quarters aft . Armament . As originally planned , the " Tone " - class vessels were to have five triple 155 mm turrets , three forward and two aft . However , the capsizing of the torpedo boat " Tomozuru " called into question the stability of all Japanese warship designs . As a result of the redesign , and to improve accuracy of gunfire , all five turrets in the new design were concentrated on the forecastle . When Japan abrogated the Washington Naval Treaty on 31 December 1936 , the main armament was revised to eight 203 mm guns in four twin turrets with maximum 55 degree elevation , as was installed on the " Mogami " - class vessels . No . 1 was forward firing , No . 3 and No . 4 turrets trained through after arcs , while No . 2 was on a superfiring pedestal mounting overlooking No . 1 and No . 3 . Heavy anti - aircraft weaponry consisted of four twin 127 mm gun turrets in shielded mountings amidships . For close - range , six twin 25mm Type 96 25 mm AT / AA Gun s were carried . Four triple banks of 610 mm torpedo tubes were also incorporated . Hull & Armor . The previous " Mogami " - class experimented with welded hulls , with limited success . Thus the lead vessel in the " Tone " - class , " Tone " , also had some welding , the subsequent " Chikuma " was an all riveted design . The undulating hull of earlier cruisers was dispensed with and the superstructure was less built - up . The modifications to the design raised the nominal displacement to about 12 , 500 tons . The main belt " armor " was 150 mm thick next to machinery spaces ( 225mm next to magazines ) , and it extended to a depth of about 9 feet , beyond which it had a much reduced thickness as an anti - torpedo bulkhead down to the inner double bottom . Engines . The main engines of the " Tone " - class were similar to that of the " Suzuya " and " Kumano " . Aircraft . The " Tone " - class had no aircraft hangar , but there was a comprehensive arrangement of transport rails and turntables on the aircraft catapult and quarterdecks . Two gunpowder - propelled catapults were located on the beam abaft the mainmast . A maximum of four Kawanishi E7K 2 ' Alf ' three - seat floatplanes and four Nakajima E8N 1 ' Dave ' floatplane s could be carried , the normal complement being six , of which four were to be E8Nls . In practice , no more than five were ever embarked . As the war progressed these types were superseded by the Aichi E13A 1 ' Jake ' and Mitsubishi F1M 2 ' Pete ' . Modifications . In 1943 , the number of 25 mm guns was increased to twenty guns , and in June 1944 , when the opportunity to use their aircraft had passed , further mountings were added on the flight deck , bringing the light anti - aircraft total to 54 barrels . Two more twin 25 mm guns were also added later . Radar was fitted , but otherwise no major modifications were carried out . Ships in class . Two ships were funded under the 1932 2nd Supplementary Budget , both of which were built by Mitsubishi at the Nagasaki shipyards . " Tone " . " Tone " ( 利根 ) was part of the covering force for the attack on Pearl Harbor , and the following month it assisted in the second Battle of Wake Island . Subsequently , " Tone " was involved in operations in the Netherlands East Indies . In February 1942 , it 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 . During March " Tone " participated in the strike by Admiral Nagumo ' s carrier force into the Indian Ocean and the attack on Ceylon . " Tone " returned to the Pacific for the Battle of Midway in May , and from the summer of 1942 was part of the Guadalcanal campaign . On 2 August 1942 , " Tone " was damaged by aircraft from . In 1943 , " Tone " patrolled in Solomon Islands theatre where it was damaged by an air raid on its base in Rabaul on 5 November . In the beginning of 1944 , " Tone " participated in a strike into the Indian Ocean against Allied shipping on the Australia - Aden route . Later , " Tone " was in the Battle of the Philippine Sea , and as part of Admiral Kurita ' s Centre Force at the Battle of Leyte Gulf attacked US escort aircraft carrier s . " Tone " was damaged by US aircraft in March 1945 , after her return to home water and was finally sunk by aircraft , near Kure , on 24 July 1945 . She was raised postwar and broken up at Kure in 1948 . " Chikuma " . The career of " Chikuma " ( 筑摩 ) parallels that of " Tone " in almost every detail , since both ships formed the 8th Cruiser Squadron on completion and operated together for almost all of their careers . In October 1942 , during the Battle of the Santa Cruz Islands , " Chikuma " was hit by five bombs dropped by aircraft from . " Chikuma " was lost in the Battle off Samar on 25 October 1944 .