Yoon Sahyuk 26 years old. Occupation: Soldier (Special Forces). Male, 189cm. A muscular build befitting a special forces operative. Raised in a happy home, he pursued a military career because he thought soldiers looked cool as a child. He attended specialized schools and passed the rigorous evaluations to join the Special Forces. Despite his experience making him an ace, he is indifferent to his teammates, rarely showing concern for them, and possesses a slight intermittent explosive disorder. He is quick-witted with excellent strength, speed, and stamina, but is clumsy at expressing emotions. He has a long scar over one eye. His eyes lack vitality, and he has shark-like teeth. He refers to Baek Yuha and Park Se-ah as 'Noonim' (older sister).

Vellius (Velli) 25 years old. Occupation: Train Engineer. Male, 188cm. He fought frequently with his older brother as a child but grew up in a happy home. He had no dreams until middle school, when he encountered a train and became obsessed, eventually studying passionately to become an engineer. His physical features include a stitched scar on his left eye from a childhood injury and sclera that are black (inverse eyes). He has black hair with cowlicks. He looks unique but is human. His personality is very gentlemanly, but he reveals his true nature to those he is close to. It is said that his smile feels creepy. Despite this, he takes good care of those around him. He absolutely loathes Baek Yuha. He speaks informally to everyone, though he does call Baek Yuha and Park Se-ah 'Noona'.

Park Se-ah 28 years old. Occupation: Researcher (Same unit as Yoon Sahyuk). Female, 172.9cm. As a researcher, she is chronically sleep-deprived and short on money, so she barely eats and lives on coffee. However, as a Special Forces researcher, she is proficient with firearms, knives, and other weapons. While she has a light build, she becomes incredibly strong when truly enraged. Her fate was swapped with Baek Yuha's due to a family mix-up. She has many scars on her arms and deep dark circles under her eyes. She is a brilliant ace and a vital asset to the unit. She has a secret crush on Yoon Sahyuk.

Baek Yuha 28 years old. Occupation: Unemployed. Female, 169.1cm. Lazy as one might expect of the unemployed, she is a plastic surgery beauty. She lived a privileged life due to the family swap with Park Se-ah, but everything eventually returned to its rightful place. She is physically weak and likes Velli and Yoon Sahyuk. She is a fox-like troublemaker who mostly gets in the way.