The J/CB/1937 design is huge

The J/CB/1937 design is huge. If I had not reduced the armour basis to 14in, it would have been even larger. I guess that a ship that has 12-18in guns, a speed of 33 knots, and a range of 12,000nm at 15 knots needs to be large to do all that. That is especially true when the 8in armour deck and 8in anti-torpedo bulkhead are considered. the design is extremely well-protected against underwater attack. The defence against gunfire is less effective, but is adequate for a battlecruiser. Consider that the battleship counterpart has an 18in armour basis. This is the Springsharp report:

J/CB/1937, Japan Battlecruiser laid down 1937

Displacement:
 87,795 t light; 91,693 t standard; 97,800 t normal; 102,686 t full load

Dimensions: Length overall / water x beam x draught
 1,031.78 ft / 1,025.00 ft x 125.00 ft x 35.00 ft (normal load)
 314.49 m / 312.42 m x 38.10 m  x 10.67 m

Armament:
      12 - 18.00" / 457 mm guns (4 mounts), 2,916.00lbs / 1,322.68kg shells, 1937 Model
   Breech loading guns in turrets (on barbettes)
   on centreline ends, evenly spread, 4 raised guns - superfiring
      12 - 6.00" / 152 mm guns (4x3 guns), 108.00lbs / 48.99kg shells, 1937 Model
   Quick firing guns in turrets (on barbettes)
   on side, all amidships
      24 - 5.00" / 127 mm guns (12x2 guns), 62.50lbs / 28.35kg shells, 1937 Model
   Dual purpose guns in deck mounts with hoists
   on side, evenly spread, 6 raised mounts
      64 - 2.24" / 57.0 mm guns (32x2 guns), 5.65lbs / 2.56kg shells, 1937 Model
   Anti-aircraft guns in deck mounts 
   on side, evenly spread, 18 raised mounts
 Weight of broadside 38,150 lbs / 17,304 kg
 Shells per gun, main battery: 90

Armour:
   - Belts:  Width (max) Length (avg)  Height (avg)
 Main: 14.0" / 356 mm 680.00 ft / 207.26 m 9.00 ft / 2.74 m
 Ends: Unarmoured
 Upper: 12.0" / 305 mm 680.00 ft / 207.26 m 8.00 ft / 2.44 m
   Main Belt covers 102 % of normal length

   - Torpedo Bulkhead:
  8.00" / 203 mm 680.00 ft / 207.26 m 34.00 ft / 10.36 m

   - Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
 Main: 14.0" / 356 mm 13.0" / 330 mm  14.0" / 356 mm
 2nd: 6.00" / 152 mm 6.00" / 152 mm  6.00" / 152 mm

   - Armour deck: 8.00" / 203 mm, Conning tower: 14.00" / 356 mm

Machinery:
 Oil fired boilers, steam turbines, 
 Geared drive, 6 shafts, 363,186 shp / 270,936 Kw = 33.00 kts
 Range 12,000nm at 15.00 kts
 Bunker at max displacement = 10,993 tons

Complement:
 2,764 - 3,594

Cost:
 £46.297 million / $185.189 million

Distribution of weights at normal displacement:
 Armament: 4,769 tons, 4.9 %
 Armour: 37,331 tons, 38.2 %
    - Belts: 6,446 tons, 6.6 %
    - Torpedo bulkhead: 6,844 tons, 7.0 %
    - Armament: 7,336 tons, 7.5 %
    - Armour Deck: 16,065 tons, 16.4 %
    - Conning Tower: 640 tons, 0.7 %
 Machinery: 10,066 tons, 10.3 %
 Hull, fittings & equipment: 35,630 tons, 36.4 %
 Fuel, ammunition & stores: 10,005 tons, 10.2 %
 Miscellaneous weights: 0 tons, 0.0 %

Overall survivability and seakeeping ability:
 Survivability (Non-critical penetrating hits needed to sink ship):
   142,830 lbs / 64,787 Kg = 49.0 x 18.0 " / 457 mm shells or 27.1 torpedoes
 Stability (Unstable if below 1.00): 1.15
 Metacentric height 9.2 ft / 2.8 m
 Roll period: 17.4 seconds
 Steadiness - As gun platform (Average = 50 %): 54 %
   - Recoil effect (Restricted arc if above 1.00): 0.75
 Seaboat quality  (Average = 1.00): 1.08

Hull form characteristics:
 Hull has a flush deck
 Block coefficient: 0.763
 Length to Beam Ratio: 8.20 : 1
 'Natural speed' for length: 32.02 kts
 Power going to wave formation at top speed: 53 %
 Trim (Max stability = 0, Max steadiness = 100): 50
 Bow angle (Positive = bow angles forward): 6.00 degrees
 Stern overhang: 3.00 ft / 0.91 m
 Freeboard (% = measuring location as a percentage of overall length):
    - Stem:  36.00 ft / 10.97 m
    - Forecastle (20 %): 29.00 ft / 8.84 m
    - Mid (67 %):  29.00 ft / 8.84 m
    - Quarterdeck (15 %): 29.00 ft / 8.84 m
    - Stern:  29.00 ft / 8.84 m
    - Average freeboard: 29.56 ft / 9.01 m

Ship space, strength and comments:
 Space - Hull below water (magazines/engines, low = better): 83.7 %
  - Above water (accommodation/working, high = better): 216.9 %
 Waterplane Area: 108,545 Square feet or 10,084 Square metres
 Displacement factor (Displacement / loading): 102 %
 Structure weight / hull surface area: 243 lbs/sq ft or 1,188 Kg/sq metre
 Hull strength (Relative):
  - Cross-sectional: 1.02
  - Longitudinal: 0.99
  - Overall: 1.00
 Hull space for machinery, storage, compartmentation is adequate
 Room for accommodation and workspaces is excellent