Armament as completed consisted in 10 8-inch (203mm) guns in five twin turrets, four 4.7-inc (120mm) guns in four single mounts and two single 40mm vickers machine guns mounted on sponsons abaft the rear funnel; Nakajima E4N seaplanes composed the airwing.
Her fittings where almost identycal to those of Takao, a slighy different rigging and layout of the steam pipes around the funnels distinguished the ships; also the newer Nakajima E8N made up for the airwing in place of the older E4N.
The original anti-aircraft armament composed by two single 40mm manufactured by vickers fitted on sponsoned platforms abaft the rear funnel was replaced with two quadruple Hotchkiss 13mm machine, airwing was composed by 2 Nakajima E8N and one Kawanishi E7K; also, 6 directors (3 on each side) removed around the bridge area.
To correct the topweight issues after the infamous Tomozoru capsizing and fourth fleet incidend, The first two ships of the class, Takao and Atago, underwent a massive reconstruction between 1937 and 1938:
the hull was bulged, the bridge extensively recontructed, lowered and streamlined, the mainmast was moved nearly 25 meters aft, the hangar removed, the catapults replaced and moved forward, the foremast too was reduced in height; the original 4 twin banks of torpedo tubes where replaced with four quadruple ones capable of firing the Long Lance torpedo, finally AA armament was now composed of 4 twin 25mm mounts abaft the funnels and two twin 13mm mounts fitted in sponsons in the bridge area
the other two ships of the class, Takao and Maya, where originally supposed to be refitted like Takao and Atago, but shortage of avaliability in drydocks and the subsequent start of WWII led to a much smaller refit:
the hull remained virtually unchanged, the foremast was slighty modified to reduce it's height, the four twin banks of torpedo launchers where modified to accomodate the Long Lances and AA suite was refurbished with the fitting of four 25mm and 4 13mm machine guns in twin mounts like on Takao and Atago; by 1941 the Mitsubishi F1M2 and the Aichi E13A1 had superseeded the older Kawanishi E7K and Nakajima E8N.
by the end of 1942 the first two ships where further modified, the 4 single 4.7-inch guns where replaced by 4 twin 5-inchers, and the twin 13mm mounts fitted on sponsons abaft the bridge where replaced by twin 25mm ones
Sporting the same armament layout of Takao, atago could be distinguished from her sister ship by looking at the different arrangement of steam pipes around the funnels and drainage pipes around the bulges.
Anti-Aircraft was increased to 6 twin 25mm mounts by replacing the twin 13mm mounts near the bridge, also the forward sponson for the lookout with it's own searchlight was removed.
She recieved the type 21 air search radar on the foremast, two extra 25mm twin mounts above the hangar (for a total of 8 25mm twins) and an extra machine gun director abaft the rear funnel.
After recieving the type 21 air search radar Takao had the anti-aircraft armament increased with the fitting of two triple 25mm mounts on sponsons abaft the rear fire control tower, also the midship superstructure was slighty enlarged.
During her final refit in early 1944 Atago recieved a type 13 and type 21 air search radars and a type 22 surface search radar, all of them fitted on the foremast, the midship superstructure was enlarged like on Takao and a small extension to the bridge wings was also implemented; anti-aircraft armament was increased to reach a final layout of 4 triple, 8 twin and 25 single 25mm machine guns, and finally like the her sisters most of the portholes where removed in order to increase watertight integrity.
Before the Philippine Campaign (during wich the ship will end up sinking after the Battle of Samar) Chokai recieved numerous minor refits like the addition of a type 13 air search and a type 22 surface searc radars on the foremast, modification to bridge and superstructure and the addition of 2 twin and 22 single 25mm machine guns, bringing the total to 42 barrels (10 twins, 22 singles), the more visible one tough was the removal of most of the portholes in order to increase watertight integrity.
Chokai was originally scheduled to be converted into an anti-aircraft cruiser like her sister Maya, but works where postponed, and her eventual sinking prevented any possible work to be done; Chokai was the only Takao class cruiser to retain the single 4.7-inch guns trough all her career and never beign fitted with anti-torpedo bulges.
Heavily damaged during the US air raid on Rabaul in november 1943 Maya returned to japan in order to underwent repairs, during the works she was also converted into an anti-aircraft cruiser:
Anti-torpedo bulges where added, a type 13 air search radars and a type 22 surface search radar where fitted on the foremast to argument the type 21 air search radar already fitted in 1943, the mainmast was slighty reduced in height and most of the portholes where removed in order to increase watertight integrity like all her sister ships.
Turret number 3 was removed replaced by two twin 5-inch (127mm) mounts, the original 4 single 4.7-inch (120mm) guns where also replaced by 4 twin 5-inch guns for a total of 12 barrels; the four twin torpedo tubes where removed and replaced by four quadruple ones, altough no reloads where carried, light AA was increased to 13 triple and 9 single 25mm machine guns, the latter later increased to 23; before the Philippine Campaign another 4 single 25mm and 36 single 13mm machine guns in dismountable fittings where also added.
Heavily damaged during the Philippine Campaign Takao limped back to Singapore where she was moored to serve as a floating anti-aircraft platform in company of the the crippled Myoko; seaplanes where landed and anti-aircraft armament increased to 4 trilpe, eight twin and 30 single 25mm machine guns mounts, most of the portholes where already been plated over in 1944 to increase watertight integrity. The ship also recieved green camouflage.
(Camouflage scheme thanks to Colosseum)