The C6N originated from a 1942 Imperial Japanese Navy specification for a carrier-based reconnaissance plane with a top speed of 350 knots (650 km/h) at 6,000 m and range of 2,500 Nautical miles (4,960 km) [REF].
The first flight was on 15 May 1943, with the prototype demonstrating a speed of 639 km/h (345 kt, 397 mph) [REF].