Supporting
Kang Ha-kyung as Corporal Kim Gwan-cheol, in charge of the second barracks; a soldier who is the real power at the Ganglim outpost.
Lim Ji-ho as Tak Mun-ik
An administrative soldier at the Ganglim outpost and Kang Seong-jae's direct superior. Sitting in the administrative office allows him to quickly learn of rumors and gossip, making him the base's source of information. As the most educated person at the outpost, he is caught in a vicious cycle where everything is attributed to his academic background, for better or for worse. Upon joining the military, he felt his faith in humanity fading as he realized that people like those he encountered actually exist.
Kang Jun-kyu as Joo Sang-wook
A supply corporal, who is a typical sociable person, popular with his superiors and subordinates due to his talkativeness. He claims to have worked for a telecommunications company outside the military, though it is later revealed that he was actually just a phone salesman.
Lee Sang-jun as Cha Seung-woo
A sergeant and deputy platoon leader. Although a newcomer himself, he strives to appear tough in front of the soldiers. He complains about Sergeant Park Jae-young, whom everyone else avoids, but who becomes his only drinking buddy.
Kim Mun-gi as Pyo Ji-yong
A soldier and troublemaker in Ganglim Outpost.
Jung Woong-in as Lieutenant Colonel Baek Chun-ik, commander of the 1st Battalion . He listens attentively to even the most trivial stories of his soldiers, while possessing a subtle charisma that instills tension in junior officers with his mere presence. But he has a humanist side; he loves home-cooked meals with seven side dishes that he shares with his family and seeks to strengthen the soldiers through food.
Han Min as Captain Lee Min-gu, head of the logistics support section at the 1st Battalion headquarters and Lieutenant Colonel Baek Chun-ik's loyal right-hand man. He is an ambitious character who would do anything for a promotion.
Lee Se-ho as Major Im Seung-bin
At the Korea Military Academy, Seung-bin was an unremarkable cadet. After his rapid promotion to Major, he became a high-profile officer but failed to realize that his rising fame also attracted more enemies.
Park Seo-ri as HR Officer, Senior Manager Heo Ran-hee
Seo Jeong-yeon as Gong Su-yeon
Seong-jae's mother.
Choi Deok-moon as Kang Il-yong
Seong-jae's father.
Cho Yu-ha as Kang Eun-jae
Seong-jae's younger sister.
Jeon So-young as Jung Min-ah, with whom Seong-jae had a relationship before his enlistment and whom he meets again now, as she is a trainee reporter for the Korea Defense Daily.
Jung Jae-sung as General Kim In-tae, head of the 29th division and a graduate of the Korean Military Academy, who highly values Kang Seong-jae's abilities and supports him unconditionally.
Ahn Gil-kang as Bae Won-yeong
The commander of the 60th Regiment. With his imposing presence, he is the very image of a born soldier. He commands the stage with a straightforward personality that matches his image. However, he has a very discerning palate, which keeps the cooks at the Ganglim outpost on edge.
Oh Seung-baek as Corporal Lee Ho-young, a culinary prodigy who works at a military officer's kitchen. He cooked duck confit served with an orange gastrique on the promotion day.