The resulting design, the Kawanishi K-8A, was a single-engined monoplane with a fabric covered wooden structure.

It was powered by a 305 hp (227 kW) Maybach Mb.IVa water-cooled inline-engine, as used in Kawanishi's successful K-7 biplane, but was larger and heavier than the K-7.

The aircraft demonstrated relatively poor performance, but showed good stability, making it popular for long-distance flights.

A total of 5 K-8As were completed in 1926, all going to Nippon Koku K.K..[1] The design attracted the attention of the Teiko Kaibo Gitai, (the Imperial Maritime Defence Volunteer Association), a patriotic organization, who placed an order for two modified aircraft, the Kawanishi K-8B, with reduced span wings, a slimmer fuselage and the crew cockpits moved rearwards.

They were then leased free-of-charge to Nippon Koku on the condition that they would be transferred to the Imperial Japanese Navy on request.