High Quality Content by WIKIPEDIA articles! The Nakajima Ki-84 Hayatewas a single-seat fighter used by the Japanese Imperial Army in World War II. The Allied codename was "Frank"; the Japanese Army designation was Type 4 FighterRobust, capable, with excellent performance and maneuverability and powerful armament, the Ki-84 was considered to be the finest Japanese fighter to see large scale operations during the Second World War. Though hampered by poor production quality in later models, a high-maintenance engine, and lack of experienced pilots above all else, the Hayates that arrived in the Philippines proved to be very difficult opponents for American pilots.