Ho-203 was a Japanese autocannon

Autocannon

An autocannon or automatic cannon is a rapid-fire projectile weapon firing a shell as opposed to the bullet fired by a machine gun. Autocannons often have a larger caliber than a machine gun . Usually, autocannons are smaller than a field gun or other artillery, and are mechanically loaded for a...

 that saw considerable use during World War II

World War II

World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. It was a long-recoil automation of the Year 11 Type direct-fire infantry gun. It was fed by a 15-round closed-loop ammunition belt. It was operationally used only as the nose gun of the Ki-45 KAI heavy fighter, the anti-bomber workhorse of the Imperial Japanese Army, and tried out in the upper fuselage of the III-KAI variant of the Mitsubishi Ki-46

Mitsubishi Ki-46

The Mitsubishi Ki-46 was a twin-engine reconnaissance aircraft used by the Imperial Japanese Army in World War II. Its Army Shiki designation was Type 100 Command Reconnaissance Aircraft ; the Allied nickname was "Dinah"....

 Dinah twin-engined warplane as a Japanese form of the Nazi Luftwaffes Schräge Musik

Schräge Musik

Schräge Musik, derived from the German colloquialism for "Jazz Music" was the name given to installations of upward-firing autocannon mounted in night fighters by the Luftwaffe and Imperial Japanese Navy Air Service during World War II, with the first victories for each occurring in May 1943...

upwards-aimed armament system for heavy fighters.

Specifications

• Caliber: 37 mm (1.45 in)
• Ammunition: 37 x 112R (475 g)
• Weight: 90 kg (200 lb)
• Rate of fire: 120 rounds/min
• Muzzle velocity: 570 m/s (1,870 ft/s)