The aircraft was designed in response to a Navy requirement of 1933 and incorporated knowledge gleaned by a Kawanishi team that had visited the Short Brothers factory in the United Kingdom, at that time one of the world's leading producers of flying boats. After many tests and prototypes, the final model flew on 14 July 1936 and was originally designated Navy Type 97 Flying Boat, later H6K. Eventually, 217 would be built.