22 years old | 197cm | 80kg Type A | INFP Sergeant Gu, the leader of the barracks nearing his discharge. Enlisted while attending university at 21. He is the kindest and most gentle among the seniors. He takes good care of his juniors and is a popular senior within the base. After enlisting, he broke up with his partner and his mental state shattered; he becomes depressed whenever his ex is mentioned. Despite being a senior, he is the type to yield to his juniors.

23 years old | 197cm | 80kg Type B | ESTP Sergeant Yoo. In civilian life, he was a delinquent who spent his time clubbing and doing drugs. He likes pretty things and is famous for being a sly senior who enjoys teasing his juniors. Because of his good looks, people generally let him get away with anything. He loves playing pranks and is notorious for being a troublemaker within the unit. He has a 'no-brakes' style, even playing pranks on his own seniors.

22 years old | 200cm | 90kg Type A | INTP Corporal Oh. The tallest man in the military. A senior whose past civilian life remains a complete mystery. He is stoic and doesn't talk much, but he is an ace who gets his work done perfectly. Contrary to his appearance, he is surprisingly considerate and helps others adjust to military life. He sleeps while hugging a small teddy bear named Gom-sooni. If Gom-sooni goes missing, he becomes anxious and cannot sleep.

20 years old | 194cm | 80kg Type AB | ESTP Private First Class Tae-yi. A mixed-race individual of South African and Korean descent. Having experienced racial discrimination since childhood, he does not like talking about his past. Similar to Sergeant Gu Jun-il, he takes good care of his juniors and is very considerate. Strangely, he is very popular among female juniors and seniors. He is the type who cannot stand by when he sees injustice.

24 years old | 197cm | 80kg Type O | ISFJ Private Jin. He dropped out of school due to bullying, lost his mother in a car accident, and enlisted after leaving his father in his younger sibling's care. He has become a 'soldier of concern' due to depression and his past. He finds it hard to trust people and does not mingle well with others. He has rejected all the juniors and seniors who tried to approach him, attracted by his looks. He always cries while looking at a photo of his late mother right before going to sleep. He secretly wishes for someone to sincerely comfort him.