The J/CL/1923 is a lot of ship for the armament

The J/CL/1923 is quite large, although there are improvements over its predecessor. The freeboard was increased by a foot, the range was increased dramatically to 7,500nm at 15 knots, and the armament was slightly increased. The 21in TT were replaced by 24in TT, while the main armament was increased from 6in QF guns to 155m (6.1in) QF guns. Otherwise, there were no changes, but the roll period was increased to 13.1 seconds. This is the Springsharp report:

J/CL/1923, Japan Light Cruiser laid down 1923 (Engine 1933)

Displacement:
 10,085 t light; 10,463 t standard; 11,500 t normal; 12,329 t full load

Dimensions: Length overall / water x beam x draught
 629.54 ft / 625.00 ft x 57.00 ft x 20.00 ft (normal load)
 191.88 m / 190.50 m x 17.37 m  x 6.10 m

Armament:
      8 - 6.10" / 155 mm guns (4x2 guns), 113.62lbs / 51.54kg shells, 1923 Model
   Quick firing guns in turrets (on barbettes)
   on centreline ends, evenly spread, 2 raised mounts - superfiring
      6 - 4.70" / 119 mm guns in single mounts, 51.91lbs / 23.55kg shells, 1923 Model
   Anti-aircraft guns in deck mounts with hoists
   on side, all amidships
      24 - 2.24" / 57.0 mm guns (12x2 guns), 5.65lbs / 2.56kg shells, 1923 Model
   Anti-aircraft guns in deck mounts 
   on side, all amidships, 8 raised mounts - superfiring
 Weight of broadside 1,356 lbs / 615 kg
 Shells per gun, main battery: 180
 8 - 24.0" / 609.6 mm above water torpedoes

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 3.00" / 76 mm 475.00 ft / 144.78 m 12.00 ft / 3.66 m
 Ends: Unarmoured
   Main Belt covers 117 % of normal length
   Main belt does not fully cover magazines and engineering spaces

   - Torpedo Bulkhead:
  1.00" / 25 mm 475.00 ft / 144.78 m 19.00 ft / 5.79 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 3.00" / 76 mm 2.00" / 51 mm  2.00" / 51 mm

   - Armour deck: 1.00" / 25 mm, Conning tower: 3.00" / 76 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 2 shafts, 131,907 shp / 98,403 Kw = 35.00 kts
 Range 7,500nm at 15.00 kts
 Bunker at max displacement = 1,866 tons

Complement:
 554 - 721

Cost:
 £3.006 million / $12.026 million

Distribution of weights at normal displacement:
 Armament: 170 tons, 1.5 %
 Armour: 1,708 tons, 14.8 %
    - Belts: 693 tons, 6.0 %
    - Torpedo bulkhead: 334 tons, 2.9 %
    - Armament: 181 tons, 1.6 %
    - Armour Deck: 466 tons, 4.1 %
    - Conning Tower: 33 tons, 0.3 %
 Machinery: 3,843 tons, 33.4 %
 Hull, fittings & equipment: 4,364 tons, 38.0 %
 Fuel, ammunition & stores: 1,415 tons, 12.3 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   10,608 lbs / 4,812 Kg = 93.4 x 6.1 " / 155 mm shells or 1.4 torpedoes
 Stability (Unstable if below 1.00): 1.27
 Metacentric height 3.3 ft / 1.0 m
 Roll period: 13.1 seconds
 Steadiness - As gun platform (Average = 50 %): 54 %
   - Recoil effect (Restricted arc if above 1.00): 0.40
 Seaboat quality  (Average = 1.00): 1.08

Hull form characteristics:
 Hull has rise forward of midbreak
 Block coefficient: 0.565
 Length to Beam Ratio: 10.96 : 1
 'Natural speed' for length: 25.00 kts
 Power going to wave formation at top speed: 60 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 5.00 degrees
 Stern overhang: 2.00 ft / 0.61 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  29.00 ft / 8.84 m
    - Forecastle (20 %): 24.00 ft / 7.32 m
    - Mid (67 %):  24.00 ft / 7.32 m (16.00 ft / 4.88 m aft of break)
    - Quarterdeck (15 %): 16.00 ft / 4.88 m
    - Stern:  16.00 ft / 4.88 m
    - Average freeboard: 21.76 ft / 6.63 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 185.2 %
  - Above water (accommodation/working, high = better): 150.7 %
 Waterplane Area: 25,213 Square feet or 2,342 Square metres
 Displacement factor (Displacement / loading): 107 %
 Structure weight / hull surface area: 100 lbs/sq ft or 488 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 0.96
  - Longitudinal: 1.47
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is cramped
 Room for accommodation and workspaces is excellent