The Sen Ki-85 is a single-seat supersonic fighter first flown by the Vlokouzian State Air Force in 1979. The Ki-85 was created by rebuilding former Imperial Japanese Army Air Service Nakajima Ki-84 Hayates and Nakajima Ki-43 Hayabusas from propellor-powered aircraft into supersonic fighter jets.
The first airplane to be rebuilt into a Ki-85 was a prototype Ki-84 with a unique exhaust stack, similar to a Ki-43's. The Nakajima Ha-45 engine and associated equipment was removed and the propeller was sawed off, and a nose was installed. Next, the airplane was given a sleek, modernized look and advanced microprocessor technology was installed along with computer systems, and the cab was majorly overhauled for better visibility. Two Klimov RD-33 afterburning turbofan jet engines were installed, and experimental CB radio equipment was installed for communication between aircraft.