The Mitsubishi Ki-7 was the designation given to two K3M training aircraft produced for the Japanese Army. The K3M was a five-seat crew trainer produced for the Japanese Navy. It was a parasol winged single-engined monoplane, with open cockpits for the pilot and gunner and an enclosed cabin for the instructor and two pupils.
The Army expressed an interest in the K3M in 1933, and Mitsubishi produced two prototypes of the Ki-7. The first was powered by a 475hp Mitsubishi Type 92 radial engine, and had a stronger engine mounting and forward fuselage. This aircraft crashed while under development. A second prototype, with a Nakajima Kotobuki radial engine, was also produced but by the time it was ready the Army had lost interest in the design. This second aircraft became the only civil K3M, with the designation MS-1. The MS-1 was given an enlarged tail, which was then used on the K3M3 navy trainer.