Despite its antiquated appearance, the Ki-1 was used in Manchukuo and in North China during the early stages of the Second Sino-Japanese War in areas where danger from enemy fighter aircraft was minimal.

However, as soon as 1930, this advantage was lost due to British developments such as the Bristol Bulldog fighter, and Junkers was not successful in selling the design.

In 1931, representatives of Mitsubishi from Japan visited the Limhamn facilities to study some of the military conversions of Junkers aircraft.

The sole K 37 prototype S-AABP (ex D-1252 - S 36-prototype), as well as all development papers, were purchased in part by funds raised by donations in Japan.

[1] The K37 prototype was brought to Japan and tested in combat during the Manchurian Incident of 1931, following which the Imperial Japanese Army Air Force authorized Mitsubishi to produce both heavy and light bomber variations.