Nagara as of 1922:
Abukuma as of 1925:
Yura as of 1927:
Yura as of 1930:
Yura as of 1931:
the original foldable spring catapult was replaced by a standard model 2 one, still fitted on the take-off platform, the bridge structure was extended aft towards the tripod, and the cruiser embarked one of the two Yokosuka K4Y prototypes in order to test it's handling and performance before i't entry in service with the IJN as the main floatplane trainer aircraft.
Natori as of 1932:
she was the first Nagara class cruiser to underwent modifications between july 1931 and september 1932, the hangar was removed and converted into bridge space, a 4 meter-rangefinder fitted above the bridge, lookout posts where added port and starboard of the superstructure, a wireless room added between the tripod legs, fire control platforms where enlarged and a lookout post added; two lewis 7.7 machine guns where added, a kure type 2 catapult fitted between n°5 and n°6 5.5-inch (140mm) gun mounts, the original pole mainmast was replaced with a tripod one equipped with a derrick for seaplane operations, another lookout post was added to the new mainmast and two 90cm searhlights replaced the single original one; a Nakajima E4N seaplane was embarked as the reckon unit.
also the main deck was extended to port (hence not showing on drawing) from abaft the torpedo launchers to just before the n°7 gun mount.
Abukuma as of 1933:
on october 20th 1930 during night training manouvers Abukuma slammed into the side of Kitakami (a Kuma class light cruiser), the collision left only minor damage on Kutakami, but Abukuma completely lost her bow back to the n°1 5.5-inch (140mm) gun mount), luckily the bulkheads did not fail and the crippled cruiser was towed to Tateyama by Battleship Mutsu; Abukuma was then towed to Yokosuka for temporary repairs, and then to Kure.
when the cruiser exited the drydock in late 1931 her profile has become uniqe for the Nagara class, she was in fact fitted with a clipper bow, much like the one sported by the Naka (a Sendai class light cruiser), making her istantly recognizable from her sisters,
Abukuma then entered drydock again in december 1932 to bemodernized, work where completed by march 1933, her refit was much on the lines of Natori, altough with some differences: the lookout posts on the sides of the bridge where positioned forward and slight lower than the ones on Natori, rangefinder was a 3,5 meter on and the platform for the 60cm signaling searchlight was retained, the wireless room was bigger and the derrick on the mainmast was of the same type wich will be fitted on Nagara and Isuzu; still, her most distinctive feature remained the bow.
Nagara as of 1934:
she was refitted in three phases between 1931 and 1934 on the same lines of Natori, altough some details differed; the take-off platform forward of the bridge was removed, the rangefinder was a 4,5 meter one (instead the 4meter on Natori), the original two single 3-inch (76mm) anti-aircraft guns where replaced by two twin 13mm machine guns, the main deck was extended to starboard (it was port on Natori), and a single 90cm searchlight was retained on the new fitted tripod (Natori had two), the derrick for the floatplanes was also different.
Isuzu as of 1934:
refitted like Nagara she differed just because the searchlight platform ont he mainmast was positioned higher.
Yura as of 1934:
she was refitted between june 1933 and january 1934 following the same lines of the Nagara, altough her different bridge structure make her identification quite easy from her sisters, also a new RDF equipment was installed and the rangefinder was a 3,5meter one (it was a 4,5 one on Nagara)
Kinu as of 1934:
refitted from february to august 1934 kinu Looked exactly like Nagara, the differences where a built-up derrick and a 3,5meter rangefinder instead of the 4,5 one fitted on the lead ship.
Abukuma as of 1935:
reditted again between june 1934 and february 1935 while she was in reserve Abukuma had the take-off platform removed and the quadruple 13mm machine gun shifted to just in front of the bridge, the 3-inch (76mm) anti.aircraft guns where replaced with twin 13mm machine guns, a new RDF equipment was installed and a new Kawanishi E7K seaplane was embarked.
Kinu as of 1936:
during her second minor refit Kinu had the foremast heght reduced, the 7.7mm machine guns removed, the twin 13mm ones fitted abreast the fore funnel where replaced by twin 25mm machine guns, the seaplane was replaced with a more modern model and an RDF system fitted.
Abukuma as of 1938:
between april 1937 and february 1938 Abukuma underwent modifications to improve her capabilities as a destroyer squadron flagship, the bridge structure was modified rearrangin the spotting platforms and replacing the old 3,5meter rangefinder with a 6meter one, also a type 94 fire control director was added to the formest wich was also reduced in height, the twin 13mm machine guns fitted abreast the first funnel where replaced by newer 25mm ones, the original pole derrick was replaced by a built-up one, the lookout post on the mainmast was removed.
Isuzu as of 1939:
between 1934 and 1939 Isuzu underwent some slight modifications, the 7.7mm machine guns where removed and the twin 13mm ones fitted abreast the first funnel where replaced by new 25mm twins, the Nakajima E4N was repleaced by a Kawanishi E7K and the three 90cm searchlights where replaced by 110cm ones.
Natori as of 1941:
between 1932 and 1941 Natori underwant many minor refits wich led to her 1941 appearance, the flying off platfor initially retained ahead of the brighe was finally removed and the quadruple 13mm machine gun mount finally moved in front of the bridge, the foremast height was reduced, the original four 90cm searchlights where replaced by three 110cm ones, the 7.7mm machine guns where removed and the 3-inch (76mm) anti-air guns replaced by twin 25mm machine guns, boat complement was changed, a new RDF system was fitted, the seaplane upgraded to a Kawanishi E7K, depth charge embarked; finally a degaussing cable was added less than a year before the start of the war.
Abukuma as of 1941:
during the first months of 1941 the torpedo armament of Abukuma was revised, the original fit of four twin launchers was changed to four quadruple ones capable of firing the long lance torpedoes, the original fore mounts where removed and their platform plated over and converted to crew space, deptch charge where imbarked and a deguassing cable fitted, boat complement was also revised.
Nagara as of 1942:
before the start of the war Nagara had her anti-aircraft suite changed from one quadruple and two twin 13mm and two 7.7mm machine guns to two twin 25mm and two twin 13mm ones, the foremast was reduced in hieght, the searchlight changed from 90cm to 110cm ones, seaplane replaced with a Kawanishi E7K, depth charge where embarked, degaussing cambe fitted, RDF system added and boat complement revised; initially Nagara was to be modified in torpedo armament like Abkuma by mid 1941, but shortages of type92 quadruple torpedo tubes prevented it.
Yura as of 1942:
she underwent a small refit in 1938 to lower the height of the foremast, in that occasion the 7.7mm machine guns where removed and the twin 13mm ones fitted abreast the first funnel where replaced with twin 25mm ones; by the time of her sinking in october 1942 the only other changes done on her where the fitting of a degaussing cable, the boat complement beign modified and the Kawanishi E7K replacing the older Nakajima E4N.
Yura was the first IJN light cruiser to be lost during WWII.
Nagara as of 1943:
by december 1943 a type 21 air search radar was fitted above the bridge in place of the rangefinder, n°5 5.5-inch (140mm) gun mount was removed and four twin 25mm machine guns installed
Abukuma as of 1943:
by 1943 Abukuma had the type 94 director fitted on top of the foremast replaced by a type 21 air search radar, also the n°5 5.5-inch (140mm) gun mount was removed, two triple 25mm machine guns where fitted above the torpedo tubes and two 14-meter daihatsu landing craft where embarked ehile the cruiser operated in Aleutian waters
Isuzu as of 1943:
refitted between december 1942 and may 1943 Isuzu recieved two triple 25mm machine gun mounts and a twin 5-inch (127mm) gun in place of the n°5 and n°7 5.5-inch (140mm) ones, a type 21 air search radar was also fitted above the bridge in place of the rangefinder; revisions of the boat complement, addition of depth charges and fitting of the degaussing cable was implemented between 1939 and the start of the war; apparently her foremast mast was not cut down like it was done on the other Nagara class cruisers.
Kinu as of 1943:
the revision of the boat complement and degaussing cable fitting was done before the start of the war, but in 1943 Kinu underwent her main wartime modernization: a type 21 air search radar was fitted above the bridge replacing the rangefinder, n°5 5.5-inch (140mm) gun mount was removed and replaced by two triple 25mm machine guns, the n°7 mount was also removed and replaced by a twin 5-inch (127mm) one, the catapult with it's derrick was also removed and two depth charge racks where fitted at the stern.
Natori as of 1944:
after beign torpedoed in january 1943 (and completely losing her stern) Natori reached Singapore in february and was drydocked untill april 1944, during the reparis of the stern many other modifications where implemented, a type 21 air search radar was fitted on top of the bridge in place of the original rangefinder, n°5 and n°7 5.5 (140mm) gun mounts where removed, like the aircraft catapult as well as the tripod mainmast derrick, a twin 5-inch (127mm) gun mount was then fitted in place of the n°7 gun mount, also two triple and four single 25mm machine guns where fitted.
Nagara as of 1944:
by the time of her sinking in august 1944 Nagara finally underwent the torpedo tube modifications she was planned to have in 1941, the fore twin type 89 tubes where removed and their platform plated overs, the two aft postions where replaced by quadruple type 92 ones, two type 22 surface search rasdars where fitted on the sides of the bridge, two depth charge racks where fitted at the stern in place of the original single projector; the catapult was landed and, n°7 5.5-inch (140mm) gun mount was replaced by a twin 5-inch (127mm) type 89 gun, anti-aircraft armament was increased to reach a maximum of two triple, six twin and fourteen single 25mm machine guns (32 barrels) and eight 13mm machine guns.
Abukuma as of 1944:
between late 1943 and mid 1944 the Abukuma was refitted once again, the catapult and it's derrick was removed, n°7 5.5-inch (140mm) gun mount was replaced by a twin 5-inch (127mm) one, the daihatsu crafts where disembarked, lower portholes closed, anti aircraf armament increased to four triple, two twin and fourteen single 25mm machine guns (30 barrels) argumented with another ten 13mm machine guns, a type 22 surface search radar was also fitted on the mainmast.
Isuzu as of 1945:
after beign damaged at Kwajalein Atoll in november 1943 Isuzu was recalled at the Yokohama Misubishi naval Yard in order to be repaired and converted into an anti-aircraft cruiser, in september 1944 she was finally undocked, having acquired a very disctintive appearance:
all remainig 5.5-inch (140mm guns) where removed and two more twin 5-inch (127mm) guns where embarked, the original light anti-aircraft armament was also landed and replaced by 11 triple and 17 single 25mm machine gun mounts (for a total of 50 barrels), the catapult was removed and the fore twin torpedo launchers where removed and the aft ones replaced by quadruple ones, depth charge rails fitted at the stern; the bridge structure and the mainmast where also modified, the two 100cm searchlights fitted on sponson of the tripod foremast where removed and replaced by a single one, fitted on centerline between n°1 and n°2 funnels, a type 13 air search radar and a type 22 surface search radar where fitted on the mainmast, a type 21 air search radar was fitted above the bridge, beign a model A7 instead of the standard A6 her antenna was bigger, an anti-aircraft command post was also added above the bridge, wich was enclosed and fitted with windshields; finally a type94 High-angle fire control director equipped with a 4,5meter rangefinder was fitted on top of the foremast, the RDF equipment was also shifted from abaft the third funnel to the foremast.
Isuzu was Sunk on april 7th 1945, the last of the pre-war light cruisers to be sunk (the last overall, Yahagi, was sunk less then six hour later during the same day while escorting battleship Yamato in operation Ten-Go)