Mitsubishi J8M Shusui

The Mitsubishi J8M Shusui (秋水, "Autumn Water" – a poetic term for a sharp sword), was Japan's attempt to copy the German Messerschmitt Me 163 Komet rocket-powered interceptor. The project began in 1944 with only partial technical data, flown to Japan from Singapore by an officer who had travelled from Europe aboard submarine I-29; the submarine itself was sunk before reaching Japan with the rest of the material.

Designed as a point-defense interceptor against B-29 Superfortress raids, the J8M was powered by a Toku-Ro 2 (KR10) bi-fuel rocket engine burning a volatile mix of T-Stoff (hydrogen peroxide) and C-Stoff (a methanol/hydrazine hydrate mixture), known in Japan as Ko and Otsu liquids. Planned armament was two 30mm Type 5 cannons. The aircraft was intended to climb rapidly to intercept altitude, make one or two firing passes, then glide back to base.

The sole powered test flight occurred on July 7, 1945, at Yokosuka, piloted by Lieutenant Toyohiko Inuzuka (Lieutenant Commander in some English-language sources). The engine cut out at an altitude of about 350–400 m, and the aircraft crashed while trying to glide back to the field; Inuzuka died of his injuries the next day. The war ended before further testing could take place. Only seven airframes were completed. The unpowered glider variant (MXY8 Akigusa) had first flown successfully in December 1944.