Staff Writer (Updated: 5/16/2016):
Design of the Ki-45 followed standard two-engine fighter design for the time. Engines were mounted on a low-wing monoplane, each engine on either side of the streamlined fuselage. Accommodations consisted of two personnel seating in a divided glazed canopy. A single tail fin made up a standard tail assembly, giving the Ki-45 a identifiable Bf 110-like appearance. Armament of the base Ki-45 KAIa consisted of one forward-firing 20mm cannon, two 12.7mm (.50 caliber machine guns mounted in the nose and a single 7.92mm self-defense machine gun in the rear cockpit position making the Ki-45 system a most potent adversary. Provision was also allowed for up to two 551lb bombs held underwing. The Ki-45 KAIb model series appeared soon enough and was designed as a dedicated ground attack / anti-shipping variant. The system sported a 20mm cannon in the nose, a fuselage-mounted 37mm cannon, the standard 7.92mm machine gun in the rear cockpit and the system also retained the bomb-carrying provision of its predecessor. A large caliber (75mm) cannon was also trialled with the system for the anti-shipping role.
The Ki-45 would be airborne in prototype forms by 1939, though developmental setbacks would stave off production till mid-to-late September of 1941. The system was quickly thrown into action against bomber formations of the United States Army Air Force and achieved particular successes against B-24 Liberator types. A dependable and hard-hitting platform, the Ki-45 system excelled against such slow-moving targets. The Ki-45 was transformed into a dedicated nightfighter in the Ki-45 KAIc model series with obliquely-mounted 37mm cannon and advanced search radar. The C-model went on to become the definitive Ki-45. As excellent a system as Japan fielded however, the Ki-45 was relegated to homeland defense as Allied advancements in the Pacific continued to hamper offensive operations by the Japanese.