The Mitsubishi Ki-51 (Army designation is Type 99 attack aircraft; Allied codename Sonia) was a light bomber/dive bomber aircraft in service with the Imperial Japanese Army during World War II. It first flew in mid-1939. Initially deployed against Chinese forces, it proved to be too slow to hold up against the fighter aircraft of the other allied powers. However, it performed a useful ground attack role in the China-Burma-India theatre, notably from airfields too rough for many other aircraft. As the war drew to a close, they began to be used in kamikaze attacks. Total production was around 2385 units.