The Kawanishi N1K1 was designed to meet a Japanese Navy specification for a single seat floatplane fighter that was put forward in September 1940. The specification was to produce a plane that would be in forward areas protecting assault forces. The design team was Toshirhara Baba, Shizuo Kikuhara, Hiroyuki Inoue, and Elizaburo Adachi.
The N1K1 had excellent performance despite its main float and outrigger floats.
The first N1K1 prototype had a contra-rotating propeller but gearbox problems caused it to be replaced by a conventional propeller starting with the second prototype.
The prototypes had retractable outrigger floats but this was abandoned due to difficulties and fixed floats were used. The central float was attached by an I-strut and a V-strut.