Master Miller is a drill instructor and survival coach in Metal Gear.
Kazuhira Miller (カズヒラミラ), also known as McDonell Benedict Miller (マクドネル・ベネディクト・ミラー), was the subcommander of both the Militaires Sans Frontières and Diamond Dogs, and later, the survival trainer of FOXHOUND. He was well-read and possessed a vast array of scientific knowledge.
The child of an American GHQ officer and a Japanese woman, Kazuhira was born in Yokosuka of the Kanagawa Prefecture, Japan.
Kaz was conceived as a result of his mother working as a prostitute, though his father treated her as a wife. Kaz's early life in Japan was a struggle, as he was born after his father had returned to America, and could not obtain Japanese citizenship due to his father being unknown. Many Japanese children would often mock him for his Western appearance, with his blue eyes, blond hair and fair skin. Because of these factors, he identified himself more with the United States, than to the Japanese. However, his father had left his mother some money prior to leaving, which she used to set up a shop, selling items such as cigarettes to occupation troops.
When Kaz was ten years old, his mother became ill, leaving him to run the shop by himself. While his mother was bedridden, he stumbled upon a picture of his father, and began showing it to the American soldiers who came into the store, asking if they knew who the man was. He eventually learned from one of his father's students that the man was Colonel Miller, who had retired from active duty and was serving as a military instructor. Kaz knew he wanted to go to America as well as meet his father, so he eventually sent a letter to him in the U.S., requesting to travel there.
That wish was eventually granted and Kaz was picked up from his home, left his mother behind, and went to the U.S. to get an education. Kaz soon discovered that he once had a half-brother, though he had recently died in the Vietnam War, which had caused his father to enter a state of depression. Taking on his father's surname of "Miller", Kaz was supplied with money to enroll at an Ivy League school, later graduating from it and receiving his college degree. During his stay in America, he also witnessed the rise of the anti-Vietnam protests that were occurring within America. He then returned to Japan, only to find that his mother wasn't angry that he had left her behind, but that she had simply forgotten who he was entirely, her mind having been affected by a disease she contracted during her days as a prostitute. Shortly after returning, he joined the Japan Self-Defense Forces, both to pay for his mother's hospital bills, and also as a way for him to get a taste of the battlefield.