The Mitsubishi Jukogyo company began producing the Mitsubishi ki-21 bomber for the Japanese Air Force in 1936. The aircraft had a maximum speed of 302 mph (486 km) and had a range of 1,680 miles (2,700 km). It was 52 ft 6 in (16 m) long with a wingspan of 73 ft 10 in (12.10 m). The aircraft was armed with 6 machine-guns and could carry 2,205 lb (1,000 kg) of bombs.

The Mitsubishi ki-21 remained in service throughout the Second World War and took part in every major Japanese land operation.