The Koide-Taeru GJF-1, given the temporary designation D-1, was the only Kenkuni aircraft designed to meet the performance requirements of Specification 2596. The design carried 8 Type-79 Light Machine guns chambered in 7.62mm, which deviated from the specified armament of 2x1/2" machine guns and 2x3/4" cannons. The aircraft utilized an all-electric power system, meaning the flaps and landing gear were powered electrically. Power for the aircraft was furnished by 2x600 hp Koide-Taeru K-1 engines, a 2-stroke V-8 version of the Koide-Taeru K-2 engine, which utilized a complex Turbo-Compound and Turbo-supercharged setup to ensure more power available. Nevertheless, the GJF-1's evaluation was postponed. While the aircraft DID make the 300 mile per hour mark, its cruising speed was only 200 miles per hour. To make matters worse, the initial airframe proved aerodynamically unstable; the GJF-1 was lost when the aircraft went into a stall due to the center of gravity being too close to the tail. The GJF-1B came equipped with a gyroscopic stabilization system in the elevators which helped, combined with the addition of armament, and the GJF-1C was fully set up for combat, AND the wings were redesigned, which eliminated the need for the original stabilization system. However, the powerplant suffered just as badly as the airframe; The Turbo-composite Koide-Taeru K-1 engines were notoriously unreliable, and overheating was a common concern in the design. Although many of these problems were about to be fixed, the Air Force eventually rejected when the first GJF-1D took to the air. However, the Estevanian Air Navy took an interest in the design, and 25 airframes were produced for export, and 50 more were license-built. These few aircraft were able to score several victories in the Battle of Estevania. Nevertheless, it proved too little to change the course of the invasion, and all surviving aircraft were used as trainers by the Andromedian Air Force.