McDonell Benedict "Kazuhira" Miller, a.k.a. "Master" Miller, was first introduced in Metal Gear 2: Solid Snake as a drill instructor and survival coach for FOXHOUND. His character was expounded upon in Metal Gear Solid: Peace Walker and Metal Gear Solid V: The Phantom Pain. He supposedly made his second appearance in Metal Gear Solid.
Miller is voiced by Robin Atkin Downes.
Kazuhira Miller was born in 1946 to an American GHQ officer and Japanese woman, who was working as a prostitute during the American occupation of Japan. Born after his father's return to the USA, Miller struggled in Japanese society having neither a citizenship due to his father's absenteeism, nor Japanese facial features so was mocked by his peers at school. His mother though had managed to break out of the prostitution trade thanks to money left by his father before he departed; it was used to set up a shop which catered to the Allied troops still stationed in Japan.
At the age of 10, his mother fell ill and he was forced to run the shop independently. He found purpose after coming upon a picture of his father and began to ask Americans who came through if they recognized the man in the photo. After some time, the man was identified as Colonel Miller, who was now working as a Military Instructor. Kazuhira quickly made contact in the hopes of moving to America to attend university and to know more of his father. He was obliged and provided with the money necessary to attend an ivy league institution.
Kazuhira arrived to an America gripped by the Vietnam conflict, and saw its effects personally and publicly. He observed the peace rallies and learned of his recently deceased half-brother who was killed in the conflict, a fact which weighed heavily on Colonel Miller.
After completing his education, he returned to Japan to care for his mother only to find that a STI contracted while working as a prostitute (assumed to be syphilis) had induced memory loss. Kazuhira, no longer remembered by his mother, joined the JSDF to cover treatment costs and to begin developing his military career. He quickly fell out of favor with the organization though; the lack of large scale combat, as well as the lack of acknowledgement in regards to his better developed policing skills by his superiors crippled his morale. The suicide of Yukio Mishima at the JSDF HQ was the final straw, and resigned after 2 years of service.
He traveled briefly to America and learned of his father's suicide, spurred by the death of Kazuhira's half-brother, and that he was already buried. His mother died soon after his return to Japan.
Utilizing his military acumen, he sold his skills as a mercenary through the early 70's until meeting Big Boss.
Miller eventually found his way to Columbia, serving as a Drill Sargent to the local militia, where he was first bestowed the title 'Master Miller'. After 2 months of combat, Miller was caught in an ambush and subsequently injured by a booby trap. He was approached by the enemy commander, Big Boss, and sought to end both their lives rather than suffer the embarrassment of failure. He feigned submission and asked that Big Boss execute him, all the while hiding a grenade. The ruse failed and Miller was brought to the base of the government forces Big Boss was fighting for; appreciating Miller's vigor, Big Boss extended an invite to join his burgeoning mercenary outfit, Militaires Sans Frontières. Miller tried to decline, but was reminded by Big Boss that he would not make it out of the camp alive if he refused the offer due to him being a POW in the camp. Miller counter proposed that a contest should be held: they would compete in a series of survival challenges and if he won, Big Boss was to help him escape the camp with no strings attached, if he lost, Big Boss had the choice of allowing him to join MSF or leaving him in the camp. The challenge was accepted and was scheduled to begin ASAP.
While Miller was confident in his skills, he knew Big Boss would be a tough opponent, so prepared an ace-in-the-hole; in the event he lost, unaffiliated guerrillas contacted by letter would hold Boss at gun point. Miller had a similar ambition to Big Boss, to found a new type of business, but refused to be made an underling so hoped to take him alive and extend the same offer, that Big Boss join him. As the competition progressed it became clear that Miller was outmatched, the competition concluding with him having not won a single event. To further hurt his ego, Miller's ace backfired, as Big Boss had convinced the militiamen to help him instead by talking to them and utilizing his charisma, rather than sending an impersonal letter.
Miller retreated in to the jungle alone, humiliated, resolving that he could make it out of Columbia by himself. Big Boss caught up to him though and the two brawled once more, and Miller, in the end, joined MSF. He conditioned though that he be allowed to challenge Big Boss once more when he was ready.
Miller plays a largely offscreen role, offering support as Snake's Mission Control. It is implied after the game's true ending that he was secretly a double-agent for the secretive Cipher group, in order to convince Big Boss to rejoin the Patriots. He knew about the true identities of Galvez and Paz, but decided to feign ignorance so as to grow the MSF with Snake instead.
Miller can be assigned to any unit on Mother Base. His unique "Mother Base Deputy Commander" skill boosts the morale of all staff members on the team he's assigned to. Similarly to Extra Ops 67: Date with Paz, Snake can go on a Date with Kaz, the goal of which is to seduce him by using Co-Ops Communication to pay him compliments or using CQC to interrogate him, wearing the Naked uniform will boost his affinity. If the player knocks out Miller, which he somewhat enjoys, he drops the design schematic for the Patriot machine gun. S-ranking Extra Ops 68: Date with Kaz unlocks Miller's uniform which can be used by any male soldier on missions, including Snake. If the player wears the swimsuit during the mission, Miller will be wearing a speedo.
Metal Gear Solid V: Ground Zeroes
As MSF grew in power and influence, the US and UN, through the IAEA, demanded to inspect Mother Base and determine if MSF posed a threat to the world. Miller refused to allow inspectors aboard, but his refusal was soon rescinded by Huey, who claimed that getting a clean inspection from the IAEA would be beneficial. Reluctantly, Miller decided to let the inspectors in, while Big Boss went to Camp Omega to rescue Paz and Chico.
However, the inspection turned out to be a ruse, as Mother Base was destroyed by XOF forces led by Skull Face. Miller was enraged at the loss of everything he'd built, though he didn't have long to think on it when the bomb inside Paz exploded and knocked out the chopper with himself and Big Boss aboard.
Metal Gear Solid V: The Phantom Pain
Miller managed to survive the explosion, and slowly recovered inside a military hospital in Cyprus. However, Big Boss lay in a coma. Miller tried to rebuild MSF while waiting for the day when his friend would awaken, under the name "Diamond Dogs." He even built a new Mother Base near the Seychelles to serve as a launching point. Unfortunately, he lacked the charisma of Big Boss, and was unable to attract much help to his cause.
A few days before Big Boss finally awakened, Miller found himself captured by a strange unit of supernatural soldiers called the "Skulls Unit." For some reason, they didn't kill him, but left him in Soviet captivity in Afghanistan. The Soviets tortured him for information he didn't have, cutting off one arm, one leg, and one of his eyes in the process. Luckily, Big Boss managed to pinpoint his location with Ocelot's help, and rescued him from Afghanistan.
Despite the ability of the medical staff to craft robotic replacements, Miller refused to accept any treatment for his broken body. Instead, he opted to keep his body as it was, in honor of the pain he and his late comrades-in-arms suffered. He stayed on Mother Base as the Executive Officer of Diamond Dogs, keeping the base running smoothly and collecting jobs and information for the private military force while hobbling around on a cane.
However, his demeanor grows noticeably darker from the events he lived through. He demands that Big Boss kill Quiet even after their first meeting. He constantly tortures Huey for information. After the defeat of the Sahelanthropus and Skull Face, encourages a climate of fear and paranoia on Mother Base while building Big Boss into a cult figure.
Metal Gear Solid
Though Master Miller is supposedly a member of Solid Snake's radio backup, it is eventually revealed during the story that the man claiming to be Miller is in fact Liquid Snake. The real Miller had been murdered, presumably by Liquid and his men, two days before the Shadows Moses Incident.
Despite never meeting face to face and communicating purely by codec, Liquid still saw fit to disguise himself as Miller by wearing shades and fixing his hair into a mullet. This was because players could still see a portrait of Liquid whenever Snake called him up, adding to Metal Gear Solid's quirky sense of self-awareness. It's also notable that while masquerading as Miller, Liquid's codec advice is largely useless to the player, serving as little more than pep talks with no gameplay advice or benefits.