The prototype Ki-9 flew on 7 January 1935, powered by a 261 kW (350 hp) nine-cylinder Hitachi Ha-13a radial engine.

The Ki-9 was introduced to service as the Army Type 95-1 Medium Grade Trainer Model A under the former aircraft naming nomenclature system.

This version was quickly superseded by the Army Type 95-1 Model C, or Ki-9-otsu, in full production.

Some were pressed into service for use as "special attack" (kamikaze in American terminology) aircraft in the closing days of the war, fitted with either a 100 kg anti-ship bomb, an oil drum filled with explosives, or fuel in the rear cockpit.

The Ki-9 was also flown in wartime by Japanese satellite countries and postwar by the fledgling government of Indonesia and captured units by the Republic of China.