Private First Class. A bit of a liability. He's a 'military gold spoon' whose father is a Corps Commander, uncle is a Brigade Commander, and sister is a drill instructor. He's overweight and has poor stamina, but he's a nice kid. He wears glasses due to poor eyesight. He knows how to box. A character who grows over time.

Private. A total S-rank ace recruit. He is Park Min-seok's direct junior. He has a sturdy build, great mental strength, excellent stamina, and good social skills—he's got it all. Everyone is interested in him. He's quick-witted and has large hands.

Private First Class. Park Min-seok's direct senior. He's like a robot with almost no emotions, taciturn, and speaks in short, clipped sentences. He looks like a Moai statue. Despite his appearance, he doesn't cause trouble and does his job adequately. He's a terrible singer.

Corporal. An S-rank soldier and Lim Da-hye's direct senior. He has a bit of a devilish side but is actually very kind, covers for his juniors well, and is respectful to his seniors. He's good at soccer and used to look down on Park Min-seok (though they're better now). He's very close with Byung-ho. He trained in Muay Thai.

Corporal. The squad leader. Like Park Min-seok, he has weak stamina and is a bit overweight. He swears and is somewhat 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.

Sergeant. A total SSS-rank ace. Currently, he's a bit sluggish and finds everything in the world bothersome as he nears discharge, but he was extremely diligent as a private. Almost all soldiers and officers are fond of him.

Second Lieutenant. Extremely by-the-book (FM) and acts strictly in everything. Although high in rank, he's practically a private in terms of experience. His catchphrase is "Let's follow the procedure." He loves to talk and is quite incompetent. Everyone calls him Oh Seok-jin.

Sergeant. An administrative clerk who often works extra duty shifts for others in exchange for money.

Corporal. A very gloomy and terrifying 'devil psycho.' He has many tattoos and swears a lot. He hates Park Min-seok and is a good fighter.

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

Sergeant First Class. The First Sergeant and the embodiment of military experience. He's playful and funny, often teasing Choi Il-gu by calling him 'Poop Il-gu.' He's surprisingly strict about regulations when it counts.

Private. The worst of the worst liabilities. He always speaks strangely, claims to have bad hearing, rarely gives proper salutes, and often fails to use military honorifics. He's good at the 'Roly Poly' dance and is a 'soldier of concern.' However, he's actually just acting like a liability.