After the events of Pearl Harbor, the American public was shocked. Up until that time, “The Japs” had been buffoons who could never defeat the far superior forces of American.
Pearl harbor saw the vaunted battle wagons of the USN sunk, Wake island saw the USMC forced to wave the white flag, and even the American boys fighting on the Battan peninsula were forced to throw in the towel after three months of fighting a losing battle.
And when that lie, the last thread of American isolationist bullshit, was realized to be just that, people were scared. Scared California or Hawaii could be next under the boots of the Japanese.
People who had once belittled Japan now thought them a foe far above even their own true level, Marines in August of 1942 on their way to the island of Guadalcanal, were under the assumption the Japanese were master jungle fighters, men who could slip away into the jungle, and live off a of nothing in their endless quest to kill Americans.
Once the 1st Marine division was blooded, they found among the Japanese dead after the battle of the Tenaru river, photos of US women, taken off dead Marines during the fighting on Guam, likewise, US prisoners and non combat personnel were targeted no less then soldiers or Marines.
The average Marine hated, or learned to hate the “Japs” with a passion a man might love a woman, some stories say it took offers of movies and ice cream to convince USMC troops to even attempt to take POWs, all too often they afforded wounded or unarmed Japanese soldiers the same treatment they gave US POWs, no mercy.
Marines pilfered Japanese dead for trinkets, and some even “dug for Jap gold” dislodging gold fillings from teeth. The USMC hated the Japanese on a level only matched by the soldiers of the USSR’s hatred of the Germans.