One year after the N1K1-J, the Shiden-Kai was first flown on 31st December 1943 and production started a short time later. The main differences, in comparison to its predecessor, were its low-wing design, the changed tailplane and the lengthened fuselage. Furthermore the undercarriage was simplified as far as possible. Only 1/3 of the design remained the same as on the Shiden and because of the use of different materials, the new aircraft was 225 kg lighter. The machine guns were removed; instead of them it was equipped with four 20 mm cannons.