The design that emerged from this study was for an all-metal mid-wing monoplane with fabric-covered control surfaces and powered by four 1,870 hp Nakajima NK7A Mamori 11 air-cooled radial engines driving four-bladed propellers. A long ventral bomb-bay, glazed nose and twin tailfins replacing the DC-4E's distinctive triple rudder were included. The DC-4E's retractable tricycle undercarriage was retained, as well as the original wing form and powerplant arrangement. Defensive armament comprised two 20mm Type 99 Model 1 cannon (one in a power-operated dorsal and one in a tail turret), plus single-mount hand-operated 7.7mm Type 92 machine guns in the nose, ventral and waist positions.