The first prototype of the Shiden was finished in December 1942. The prototype of the N1K1-J first flew on December 27, 1942.
The N1K1 had a Homare 11 engine (1,820 HP). The Homare 11 didn't deliver the power it was supposed to and it was 45 mph / 72 kph slower than anticipated.
The mid wing also restricted pilot's vision. The undercarriage was shown to be very weak.
Three prototypes were given to the Japanese Navy but they stalled as they didn't want to acknowledge a privately developed aircraft.
The N1K2 prototype first flew on December 31, 1943. It was given to the Imperial Japanese Navy in April 1944 for testing.