Originally some A6M2s in the field were converted in 1942 to two seaters to be used for reconnaissance and command duties.
Specifications for a dedicated trainer was given in 1943. Dai-Nijuichi Kaigun Kokoshu (21st Naval Air Depot) designed the A6M2-K.
The instructor was behind the student. The trainer's seat was where the radio and other equipment was located. The student's part of the cockpit was permanently open.
Dual controls were installed. The fixed tailwheel was larger than the A6M fighters. Wheel covers and the wing cannons were removed to save weight.
A stability fin was added just in front of the horizontal stabilizer.