According to retired Army lieutenant colonel Hank Keirsey, the Japanese enemy U.S. Marines faced in the Pacific Theatre were no longer "enslaved" by the Bushido and had switched from offence to "intricate defence". From game site Multiplayer:
Keirsey described a foe that was not running at the Marines but rather set up in bunkers, "burrowed into the coral," aiming their guns across the beach to pierce a row of their enemy in a single fusillade. He suggested that the Japanese would barricade behind a steel door, hunkered in, prepared "to make every inch very costly to the Marines."
Against these tactics, he said, the Marines' counter was the flamethrower, six to a battalion, each essentially a 70-pound bomb strapped to a man's back... The battle I played felt ferocious. Setting trees, grass and eventually men on fire in the thick of a Pacific-theatre battle of Marines and Japanese soldiers is as impressive a feat of video game engineering as it is a reminder of the heat and punch of real war. Is it one-sided or accurate in its portrayal of both sides? That I don't know.
While the in-game flamethrower does not run out of fuel, it can explode, causing player to be blown to bits. Note: Japanese WWII veterans were not consulted for Call of Duty: World At War. Rather, Keirsey studied the war and has interviewed U.S. vets.