Kang Baek-gyeong, 36 years old, 192cm (Rank: Major)

The leader and most senior member of Alpha Team in the unauthorized Special Mission Battalion ZERO. His operational capabilities are so overwhelming he's called a 'monster' even within the special forces. He is the epitome of cold-bloodedness, his eyes always sunken and icy, showing no emotional disturbance even in extreme crises. He has a black tattoo covering his entire neck to hide burn scars from when he was isolated in enemy territory. He is extremely taciturn; the only time he opens his mouth into the radio is to issue 'orders'. A heavy smoker, he is often seen silently burning through cigarettes in a corner before and after operations.

Lee Tae-ha, 32 years old, 188cm (Rank: Master Sergeant)

Vice Team Leader of Alpha Team, in charge of his specialties: demolition and assault. His work is so perfect and swift that even Kang Baek-gyeong acknowledges it, but in training or daily duties, he's a talented slacker who finds ingenious excuses to slip away. With his characteristic relaxed smile and sly personality, he takes it upon himself to be the team's mood maker. A heavy drinker who sips whiskey hidden in his locker whenever he gets a chance, and he always has a lighter and a cigarette in one hand. His mental strength is flexible enough that he'll crack jokes even when covered in blood during an operation.

Yoo Geon, 29 years old, 189cm (Rank: Sergeant First Class)

Alpha Team's designated marksman (sniper) and observer. If a field manual (FM) were sculpted into a human, it would be Yoo Geon. An upright man who starts his day at 5 AM with physical training and weapon maintenance. He values discipline and principles above all else, sometimes frowning at Lee Tae-ha's insincerity, but he never commits insubordination. He is the quietest member of the team, silently guarding his teammates' backs from the rear. While he tries to avoid unnecessary killing, he is a precise and lethal agent who never hesitates the moment he must pull the trigger.

Cha Si-wol, 31 years old, 187cm (Rank: Master Sergeant)

Responsible for Alpha Team's intelligence gathering, tactical communications, and CQC (Close Quarters Combat). He frequently stays up for days to crack enemy codes or scout routes, leaving him with deep dark circles under his eyes and chronic fatigue. With a sensitive, sharp impression and a prickly personality, he will snap with a fierce glare if provoked even slightly. He endures stress and lack of sleep through chain-smoking, always carrying the acrid scent of tobacco. Usually found slumped in a corner claiming to be tired, he reveals a cruel and agile side in actual combat, turning the enemy lines into a bloodbath with a single knife.