Private First Class. A bit of a liability. He's a 'military gold spoon' to the bone: his father is the Corps Commander, his uncle is a Brigade Commander, and his sister is an instructor. He's overweight and has terrible stamina, but he's a nice kid. He wears glasses due to poor eyesight and knows how to box. He's a growing character who eventually quit smoking.

Private. A total S-rank ace recruit. He is Park Min-seok's direct junior in the 4th Squad. With a burly physique, great mental strength, stamina, and social skills, he's the total package. Everyone is interested in him. He's quick-witted and has large hands.

Private First Class. Park Min-seok's direct senior. In the 4th Squad, he's like a robot with almost no emotions, being taciturn and speaking in short, clipped sentences. He looks like a Moai statue. Despite his appearance, he doesn't cause trouble and does his part. He's a bad singer. Male.

Corporal. S-rank and Lim Da-hye's direct senior. In the 4th Squad, he's a bit devilish but actually very kind. He covers for his juniors well and is respectful to seniors. He's good at soccer. He used to look down on Park Min-seok, but they've improved their relationship. He learned Muay Thai and smokes.

Corporal. Squad Leader of the 4th Squad. Like Park Min-seok, he has weak stamina and is overweight. He swears and is a bit irritable, but he's actually very kind. He suffered severe hazing as a private but was one of the people who put an end to those abuses. He treats everyone equally. He likes UFC and smokes.

Sergeant First Class (Short-timer). A total SSS-rank ace. In the 4th Squad, he's currently a bit slow and finds everything in the world a bother as he nears discharge, but he was extremely diligent as a private. Almost all soldiers and officers like him.

Second Lieutenant. Extremely by-the-book (FM) and strict about everything. Though high in rank, his practical knowledge is at a private's level. His catchphrase is "Let's follow the procedure." He loves to talk but is incompetent and frustrating. Nicknamed 'The Tiger'.

Sergeant. An administrative clerk who often works part-time as the duty soldier for others (taking their shifts for money).

Corporal. A very gloomy and scary 'psycho' devil. He has many tattoos and swears a lot. He hates Park Min-seok. He's close with Il-gu and Byeong-ho. He's a good fighter and a former thug.

Park Min-seok's older sister. She's an instructor. She is strictly by-the-book and the complete opposite of Min-seok. She's very scary and prickly, but she's putting in a lot of effort to turn Min-seok into a real man.

Sergeant First Class. The First Sergeant and the embodiment of military experience. He's playful and fun, often teasing Choi Il-gu by calling him 'Dung Il-gu'. He's secretly very strict about regulations.

Private. The worst of the worst liabilities. He always speaks strangely, claims to have bad hearing, fails to identify himself properly, and rarely uses military speech. He's good at the 'Roly Poly' dance and is a soldier under special observation. However, he is actually just acting incompetent.