The Mitsubishi A5M, Japanese Navy designation was "Type 96 carrier-based fighter" (九六式艦上戦闘機) was a Japanese carrier-based fighter aircraft. It was the world's first monoplane shipboard fighter and the direct ancestor of the famous Mitsubishi A6M 'Zero'. The Allied reporting name was Claude.
Almost all A5Ms had open cockpits; a closed cockpit was tried, but found little favor among Navy aviators. All had fixed, non-retractable undercarriage with (except for the trainers) wheel spats.
The aircraft entered service in early 1937, soon seeing action in pitched aerial battles at the start of the Second Sino-Japanese War, including air-to-air battles with the Chinese Air Force's Boeing P-26C Model 281 "Peashooters" in what was the world's first-ever aerial dogfighting and kills between monoplane fighters built of mostly metal.
There, they proved themselves the better of every aircraft they encountered, though the Mitsubishi team continued to improve the A5M, working through versions until the final A5M4, which added a ventral drop-tank for extended range. Even though only armed with a pair of 7.7 mm machine-guns, the new Mitsubishi fighter proved effective and damage tolerant, with excellent maneuverability and a very robust construction.
Source: Wikipedia, "Mitsubishi A5M", available under the CC-BY-SA License.