This would be the A6M. It had 2 13MM Heavy Machine guns that replaced the usual rifle caliber 7.7 gun in the engine cowling. An 2 13MMs in each wing with the 2 20MM guns in each wing. My favorite version the A7M had armour plates in the windscreen, one for the pilor and self-sealing fuel tanks and also a water-methanol supercharger. INCREDIBLE PICTURE!! The A6M was built with more powerful Mitsubishi Kinsei engine.
That's impressive! I mean it! For me is quite difficult to draw airplanes totally free hand. I had to buy a scale model to draw the Ki-84 for a comic I'm working on! I drew some "100% free hand" planes in past, using some blueprints as my main refs; I'm pretty satisfied with those artworks. But working on a comic I have not enough time to be accurate without using a scale model as a reference (particularly when comes to draw wings in perspective). I prefer to use a scale model because this allows me to choose the angle I prefer.
Back to your artwork, I really really love it. The Hellcat in the background is amazing too!