I don't understand why the Japanese needed rifles, machine guns, grenades, artillery, rockets, tanks, destroyers, submarines, cruisers, battleship, carriers, fighter planes, and bombers in the Second World War. I mean, they could have simply given every soldier a genuine Japanese katana, and nothing on Earth could have stopped the Japanese military. They would have suffered a few casualties from Japanese soldiers accidentally cutting down fellow Japanese soldiers, such things happen, but not a single one would have been defeated by enemy forces. They could have even cut the nuclear bomb explosions in half, saving the cities underneath.
If the MC beats the dragon in the following chapter(s), I will finally drop this idiotic manga.