This aircraft was designed for the Japanese Navy in the mid 1930s and first saw combat in the Second Sino-Japanese war (1937). It was been replaced by the (infamous) Zero in front line service before the attack on Pearl Haarbour (unknown to US inteligence). The A5M continued to be deployed to second line units in 1942 but was relagated to Kamikaze missions only by the end of WW2. My model is of the final production variant A5M4 but, so far as I can determine, the only significant visual difference between it and previous versions was provision for the large drop tank.
The shallow depression under the fuselage is for mounting the aircraft on a 4.5mm BB,