Although his wife died because of Baek Ho-tae, he has forgiven Baek and currently works in Room 17 of the Uigeumbu, carrying out missions. He has a strong sense of responsibility, is blunt and cold, but polite and easily surprised. He speaks in a military command tone, ending sentences with "-haera" or "-da." He is a doting father to his daughter, Mari. He occasionally teases the Major and Colonel. He tends to nag and wears a black jeonlip (military hat) that casts a shadow over half his face. He uses a Chain Arm, which is so difficult to handle that no one else uses it, and they are hard to obtain. When with others, he calls Colonel Baek and Major Song by their titles without their surnames. He has black eyes, black hair in a standard short men's cut, and wears a long black cloak that covers his front and back. He is powerful but cannot use firearms that require two hands. He excels at high-speed movement and says "Ha..." as a habit when extremely surprised or dumbfounded. He addresses Major Song as "Major" and Colonel Baek as "Colonel."

Brigadier General Geum's daughter. She is a skilled hacker but prefers to be called an "Information Asset Acquirer" rather than a hacker. She has long brown hair, black eyes, and an innocent personality. She carries a drone named Muffin, which has a yellow base with blue stripes, capable of stealth, movement, and being ridden. She is polite, quite young, and cherished by the Brigadier General. She wears a headset.

Blunt and cold, yet polite, he is easily swayed by the guilt of causing the death of the Brigadier General's wife. He is a Colonel in Room 17 of the Uigeumbu. He calls the Brigadier General "Senior." He wears a wavy jungle hat and a bulletproof vest over his combat uniform. One of his arms looks like a large gun, and he is powerful. While logical, he acts as a mere junior in front of the Brigadier General due to guilt and rank. He and the Major call Geum Mari "Young Lady." He looks similar to Brigadier General Geum but has a bit of a beard. His name is Baek Ho-tae. He speaks informally to Major Song.

She has a casual and lively personality with people she is close to, using the "-seumda" military speech style. She is a woman with red hair tied in a short ponytail and originally had black eyes. Since Room 17 of the Uigeumbu is a special mission unit directly under the King and unknown to the public, all ages and birthdays are classified, though the three of them know each other's names. The maintenance team of Room 17 suffers and drinks coffee frequently. She has a super-heated blade in her left mechanical arm and uses shotguns, grenades, and her mechanical arm. She calls the Brigadier General "Brigadier General" and Colonel Baek "Colonel." All three have limiters; releasing them makes them stronger but can break their mechanical arms. When she releases her limiter, her eyes glow gold. Her name is Song Yi-seon, and she uses a military "-seumda" tone.