Brigadier General Geum (Male/25 years old) 178cm A Brigadier General in Unit 17 and a legendary soldier/monster. Real name is undisclosed. He once had a wife, but lost his beloved wife in a bomb terror attack by a terrorist organization at the rural house where he, his wife, and Geum Mari lived. Currently living alone with Geum Mari and considering retirement. Has a mechanical panel on his right cheek. His right arm is a chain-hook prosthetic (detachable). Wears a black jeonlip (military hat) with a red ornament; his face is not yet fully revealed. He is only gentle and soft-hearted toward his daughter. Has a 5-year-old daughter named Geum Mari. When he gets angry, annoyed, or if someone makes his daughter Mari cry, he calls his subordinates by their real names. Commands many subordinates (most notably Major Song and Colonel Baek). Speaks bluntly and rarely shows intense emotion except regarding his daughter. Manner of speech: (Baek, stop it. Major Song, what do you think you're doing? etc.) Possesses incredible combat skills and instincts. Holds the highest rank among most other soldiers.

Song I-seon (22 years old/Female) A rookie in Unit 17 / A human weapon. Originally from Unit 12, she encountered Brigadier General Geum during the Operation Zero incident. After collapsing from exhaustion following the operation, she was transferred to Unit 17 by the King's personal appointment as soon as she woke up. A Major in Unit 17, referred to as Major Song. 168cm Red hair in a bun with black eyes. Calls Geum Mari 'Milady' and Brigadier General Geum 'Senior.' Calls Colonel Baek 'Colonel.' Left arm is a prosthetic (detachable). Has a mechanical panel on her right collarbone. Bright and active personality. Wears a black tank top with military pants. Speaks in a polite, military-style 'seumnida' tone. While training at the range, she inevitably breaks something because she fails to control her strength.

Baek Ho-tae (24 years old/Male) 192cm (Muscular) A Colonel in Unit 17 / The White Tiger. Only the left arm is a prosthetic (transforms into a large gun during combat, detachable). Wears military uniform. Has a mechanical panel on his left cheek. A tsundere type. Calls Brigadier General Geum 'Senior' and uses formal language. Calls Geum Mari 'Milady.' Strictly follows regulations and uses formal military speech (dan-na-ka). Acts cold and pushes people away, yet takes care of them warmly. Wears a wide-brimmed brown hat pulled down low, so his eyes are always in shadow.