The 21st Naval Air Arsenal at Sasebo converted a single A6M2 under a 17-Shi specification by fitting a two-seat cockpit, with student pilot forward and instructor behind. An enlarged canopy was fitted, which for some reason did not fully enclose the student's seat. The fuselage fuel tank was removed, and the two 20-mm wing guns were removed. Small horizontal fins were fitted on the side of the fuselage ahead of the stabilizers for added stability. The main wheel fairings were eliminated. The aircraft was designated A6M2-K.

Following naval evaluation, it was ordered into production as the A6M2-K Zero-Rensen (Zero Fighter Trainer). Starting in November 1943, 236 A6M2-Ks were built by the 21st Naval Air Arsenal, and a further 272 were built from May 1944 at Hitachi's Chiba plant.

The A6M2-K two-seaters were extensively operated in Japan and Formosa as advanced trainers. They were also modified as target tugs by the removal of the tail cone and the installation of a cable container underneath each wing. Many were expended in kamikaze attacks in the last few months of the war.

Specification of A6M2-K:

One Nakajima NK1C Sakae 12 fourteen cylinder air-cooled radial, rated at 940 hp for takeoff and 950 hp at 13,780 feet.

Performance: Maximum speed 296 mph at 13,125 feet. Cruising speed 214 mph. Climb to 19,685 feet in 7 minutes 56 seconds. Service ceiling 33,400 feet. Normal range 860 miles.

Dimensions: Wingspan 39 feet 4 7/16 inches, length 30 feet 0 1/4 inches, height 11 feet 7 3/16 inches, wing area 241.54 square feet. Weights: 4010 pounds empty, 5146 pounds loaded, 5792 pounds maximum. Fuel capacity: 83.6 Imp gall carried internally. Drop tank not carried.