Banzai Charger

Banzai chargers are Japanese soldiers that will rush at the player with bayonets attached to Arisakas during combat or when attempting an ambush, (as in the level Hard Landing) yelling "Tennōheika banzai!"("May the Emperor live for ten thousand years!") or just simply "BANZAI!!". Japanese soldiers were indoctrinated to believe that surrendering was dishonorable and cowardly, and to choose death over surrender.Thus, banzai chargers are often a final stand in the face of defeat so that they could die with honor.

History
Banzai charging was an extremely effective maneuver against most forces, however, eventually the charge became ineffective to the Chinese' superior melee training and the well-trained American forces armed with semi-automatic and automatic weapons. This tactic was first used against American forces during the Battle for Attu islands by Colonel Yasugo Yamazaki of the Japanese forces garrisoned there. Towards the end of the battle, he gathered all the remaining Japanese forces on the island and charged at the U.S. forces with a katana in hand. Although only 28 Japanese soldiers out of the 1,000 were taken prisoner (none of them were officers), the attacked penetrated American defenses and shocked the rear-echlon units. However, most of the Japanese commanders chose not to use massive Banzai Charges during the war except as a final attack to avoid capture and dishonor. Towards the end of the war, American forces could easily eliminate any Banzai chargers by spraying them with their automatic weapons

Defending Against Banzai Chargers
Banzai Chargers will often jump out of tall grass, spider holes, jungles (as seen in the level Hard Landing) or out of Japanese defenses.They will often attack when least expected, such as when a player is in the middle of reloading. If a charger reaches you, he will push you down and try to impale you with a bayonet. To stop them, you will have to press a button (varies for what console you are playing on) before he stabs you so that you can push his rifle aside and stab him in the neck. For players who cannot do this at an accurate time, they should repeatedly press the action button as soon as you get pushed down. On the Xbox 360 and PS3 version, players that successfully counter a banzai charger for the first time will unlock the achievement "Close Shave" worth 10 Gamerpoints.