 The Ki-87 was developed in response to American B-29 Superfortress raids on the Home Islands.It followed up on earlier research by Nakajima and the Technical Division of Imperial Army Headquarters into boosting a large radial engine with an exhaust-driven turbo-supercharger, which had begun in 1942, well before the B-29 raids began.The efforts of the Technical Division of Imperial Army Headquarters eventually culminated into the Tachikawa Ki-94-I, while the Ki-87 was developed as a fall-back project, using less stringent requirements.