In the morning of the 7th July 1945, in the runway of the military base at Yokosuka, a group of technicians prepared a new type of aircraft which shortly later should take off for its first test flight. It was a strange aircraft, short, rather chubby, fitted with two very wide wings and totally devoid of tail planes. The test pilot, Engineer Inuzuka, occupied the cockpit, the runway was cleared, and after some moments the aircraft was launched at an impressive speed, leaving behind a trail of flames.

Reached the minimum sustentation speed, the aircraft climbed burdensomely, leaving on the ground the special take-off carriage, and it started its flight. But unexpectedly the engine stopped, and the aircraft fell like a stone, crashing against the ground and causing the death of the pilot. Technicians and projectors immediately sought the causes that had blocked the engine, and they found them in a defect of the feeding device, which was modified in a matter of few days. But the 15th August Japan capitulated. The hopes deposited in the secret weapons were already null.

The history of this unfortunate prototype, built by Mitsubishi and denominated J8M "Shusui" ("Swinging Sword"), started in July 1944, when it was attempted to transfer from Germany to Japan the prototypes of the turbojet (Me 262) and rocket (Me 163) aircraft along with their corresponding plans and construction instructions. All of this material had to be carried by two submarines. But after several "adventures" little thing arrived to Japan. Of the Me 163 arrived only the plans and the rocket engine build by Walter.

But after few months the technicians at Mitsubishi managed to reconstruct the aircraft in an almost identical way to the original one. Meanwhile, to remove dead times, it had been started a training program for a certain number of pilots. These trained with aircraft identical to the Shusui (devoid of engine, however), and because of this of the same aerodynamical characteristics, built by Maeda and Yokoi. When the J8M was ready (apart from the prototype another six exemplars with engine had been built), we already know what happened.

The Shusui was a middle-winged monoplane, devoid of tail planes, of metallic structure and mixed coating. The aircraft, devoid of landing gear, took off by means of a small carriage with two detachable wheels placed under the cockpit, which were left on the ground at the moment of take-off. For landing it was provided a retractable skid that allowed to land even in grasslands. The propulsion was given by a rocket engine Toko Ro2 fed by liquid fuel, Japanese version of the Walter HWK 509, which provided 1500 kilograms of thrust, around 200 less than the original German model, but enough to impulse the aircraft at speeds nearby to 900 kilometers/hour.

The armament comprised two 30-millimeter cannons or only one cannon, if the other were replaced by an additional fuel tank that allowed an increased operational range. It was intended that these aircraft, given their very limited operational range (little more than five minutes of flight), were used only during alarms, intercepting the formations of enemy bombers when these were close to their airfields, for, after a brief combat, promptly returning to land by gliding, for it was expected that during the action they would have depleted the fuel.