MIS Human Secret Weapon

When the US Army realized its deficiencies in intelligence operations against Japan in WWII, Japanese Americans were secretly trained to be soldiers of the Military Intelligence Service. They showed their patriotism to US, the nation that had caged their families in the internment camps by choosing to fight against the same race. Not only had they tremendously contributed to America's victory, but also to the successful recovery of Japan using their skill in language. However, the US government had kept their existence as a top secret. Who were these soldiers whom called the Human Secret Weapon?