The Japanese Imperial Navy used ground-based interceptors to protect important places such as their naval ports. Raiden (Jack) was the first interceptor of the Japanese Navy. On November 1939, aircraft manufacture, Mitsubishi Heavy Industries, received a production demand from the Japanese Navy, starting the development of Raiden under the name of 14-Shi interceptor. The aircraft was required to be capable of speed higher than 600 km/h. it was also required to possess high power, enabling it to reach an altitude of 6000m within 5 minutes 30 seconds. The only engine that fulfilled these performance demands was the 1430hp, 1.34m diameter Kasei Type 13 engine, initially developed for bomber use. The 14-Shi interceptor made its maiden flight on March 1942, but suffered from propeller problems and poor visibility. As a countermeasure, the engine was changed to the Kasei Type 23. The new production aircraft equipped with that engine made its maiden flight in October 1942. But since there were also some problems with this model such as propeller vibration, approval for practical use of the Type 11 Raiden was not given until December 1943. In the meantime, the armament-bolstered Raiden Type 21 was completed, which featured four wing-installed, belt-supplied 20mm machine guns. Raiden was first used in September 1944 in Corneo, but showed its true strength defending the skies over Japan. In particular, the 302nd Flying Group based in Atsugi took advantage of Raidens high speed and altitude capabilities to shoot down many B-29 bombers over the Kanto region of Japan.