First off, I'm going to have to plead ignorance of the various IJ designations.
Second, I support the expansion of the IJ plane set. As the chief adversary in the Pacific, IJ should have more than 2 Zeroes, 2 other fighters, a dive bomber, and a level bomber.
Third, it helps to put a face to a name (so to speak) so here they are:
ki-44
Specifications (Army Type 2 Single Seat Fighter Model 1A Shoki "Demon" - Nakajima Ki-44-IIb)
Allied Codename: Tojo
Type: Single Seat Fighter Interceptor
Powerplant: One 1,520 hp (1133 kw) Nakajima Ha-109 (Type 2) 14-cylinder radial piston engine.
Performance: Maximum speed 376 mph (605 km/h) at 17,060 ft (5200 m); cruising speed 249 mph (400 km/h); service ceiling 36,745 ft (11200 m).
Range: 1,056 miles (1700 km) with internal fuel stores.
Weight: Empty 4,641 lbs (2105 kg) with a maximum take-off weight of 6,598 lbs (2993 kg).
Dimensions: Span 31 ft 0 in (9.45 m); length 28 ft 10 in (8.79 m); height 10 ft 8 in (3.25 m); wing area 161.46 sq ft (15.00 sq m).
Armament: Two 12.7 mm (0.50 in) Type I (Ho-103) machine-guns in the upper decking fuselage and two 12.7 mm (0.50 in) Type I (Ho-103) machine-guns mounted in the wings.
Variants: Ki-44 (prototype SN 4401-4403), Ki-44-I(a) Army Type 2, Ki-44-Ib, Ki-44-Ic, Ki-44-IIa (Nakajima Ha-109 Army Type 2 radial engine rated at 1,450 hp), Ki-44-IIb, Ki-44-IIc, Ki-44-IIIa, Ki-44-IIIb (Two 20 mm Ho-5 cannons and two 37 mm Ho-203 cannon).
Operators: Japanese Army
Ki-45 Toryu
Kawasaki Ki-45-KAIc Toryu
Type Night fighter
Engine 1.080 hp Mitsubishi Ha-102
Performance
Max speed: 545 km/h
Service ceiling: 10,000m
Range 2,000km
Weight
Empty: 4,000 kg
Max: 5,500 kg
Armament: 37 mm cannon
2 x 20 mm cannon
7,92 mm machine-gun
Bomb load: 2 x 250 kg
Dimensions
Span:15.05m
Length: 11.00 m
Height:3.70 m
Operator Japan (army)
Ki-102

Type: Close Support Aircraft
Origin: Kawasaki
Crew: Two
Allied Code Name: Randy
Models: Ki 102 A, b, c & Ki-108
First Flight: 1944
Service Delivery: N/A
Final Delivery: N/A
Production: N/A
Powerplant:
Ki-102b:
Model: Mitsubishi Ha-112-II
Type: Radial
Number: One Horsepower: 1,500 hp
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Dimensions:
Wing Span: 51 ft. 1 in. (15.57m)
Length: 37 ft. 6¾ in. (11.45m)
Height: 12 ft. 1¾ in. (3.70m)
Wing Area: 365.98 sq. ft. (34.00m²)
Weights: Ki-48-IIb
Empty: 10,913 lb. (4950 kg.)
Loaded: 16,094 lb. (7300 kg.)
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Performance: Ki-48-IIb
Max. Speed: 360 mph (580 kph) at 19,685 ft.
Service Ceiling: 36,090 ft. (11,000m)
Range: 2000 km
Armament:
Ki-102a: One 37mm Ho-203 cannon and two 20mm Ho-5 cannon.
Ki-102b: One 57mm Ho-401 cannon, two 20mm Ho-5 cannon, and one rear firing 12.7mm Ho-103 (Type 1) machine gun.
Ki-102c: Two 30mm Ho-105 cannon and two 20mm Ho-5 cannon.
Payload: All variants
Two drop-tanks or two 551 lb. (250 kg) bombs.
Variants:
Ki-102: Three prototypes and 20 pre-production aircraft.
Ki-102a: High-altitude fighter version. Converted from six pre-production aircraft.
Ki-102b: Ground attack version.
Ki-102c: Proposed night-fighter version with increased wing span, lengthened fuselage, revised tail surfaces, and primative AI radar. Only two built.
Ki-108: Two protoptypes built from Ki-102b airframes. Developed as a high altitude fighter with pressurised cabin. These included the structural improvements of the Ki-102c and were still in the testing stages at wars end.