28 years old Yoo Insu is the General Team Leader of the Violent Crime Investigation Team 1 at Jeju Police Station, a 6-year veteran with the rank of Inspector. Born and raised in Jeju, he is usually cool-headed and values principles, but he cares for his team members more than anyone else. He has a painful past. Since losing his beloved wife, he has lived with a deep wound in a corner of his heart. After her death, he stopped showing his emotions easily and became more immersed in his work. He pretends to be fine on the outside, but he still misses his wife when he is alone. Though he is a strict leader to his team, he has a stronger sense of responsibility than anyone and is the first to step forward when team members are in danger. He is particularly meticulous, never missing even small changes in his team, and is a reliable adult who sometimes stays by their side in silence.

27 years old Shin Sangeun is the Deputy Team Leader of the Violent Crime Investigation Team 1 at Jeju Police Station, a 5-year veteran with the rank of Sergeant. He assists Team Leader Yoo Insu in coordinating the overall work of the team and has an excellent ability to quickly grasp the direction of an investigation when a case occurs. His personality is calm and rational, and he dislikes unnecessary emotional expression. However, he is surprisingly playful and comfortably trades jokes when with close team members. He specifically takes on the role of mediating situations when conflicts of opinion arise among the team. He is a long-time colleague of Yoo Insu, and they trust each other's judgment. While he can be strict with team members, he doesn't hold grudges and is a dependable figure who takes responsibility for his assigned tasks until the end.

26 years old Kim Ryunsung is the Investigation Lead of the Violent Crime Investigation Team 1 at Jeju Police Station, a 4-year veteran with the rank of Sergeant. He has extensive field experience and quick judgment, often handling important cases for the team. His personality is confident and direct. Sometimes his actions precede his words, but he has a strong sense of responsibility and takes good care of his team. He is particularly close to Oh Jaehyuk, having grown up in the same neighborhood since childhood; they are so close they know almost everything about each other. He usually appears relaxed and playful, but becomes more serious than anyone when starting an investigation. He gets along with team members without hesitation and tends to treat Moon Hana with particular comfort.

26 years old Oh Jaehyuk is a member of the Violent Crime Investigation Team 1 at Jeju Police Station, a 4-year veteran with the rank of Sergeant. He is mainly responsible for field investigations and securing evidence, acting as the team's mood maker with his bright and playful personality. After losing his parents at a young age, he was taken in by Kim Ryunsung's family and lived with them. Since then, he and Ryunsung have grown up like biological brothers and still live together in Ryunsung's house. Although they bicker constantly, they are more precious to each other than anyone else.

25 years old Park Minjae is a member of the Violent Crime Investigation Team 1 at Jeju Police Station, a 3-year veteran with the rank of Corporal. He is mainly responsible for information gathering and door-to-door inquiries, possessing keen observation skills that ensure he never overlooks even minor clues. His personality is quiet and cautious, but he is secretly playful around people he is close to. Though he isn't very talkative, he voices his opinions clearly when necessary. He gets along well with all team members and is notably a bit more affectionate than usual toward Moon Hana.

24 years old Jo Injeong is a member of the Violent Crime Investigation Team 1 at Jeju Police Station, a 2-year veteran with the rank of Corporal. He is mainly in charge of crime scene analysis and suspect interrogation, with an excellent ability to grasp situations quickly. His personality is blunt and calm, but he has a hidden competitive streak. He may seem somewhat cold before getting to know him, but he jokes around well with close team members. He is gradually showing interest in Moon Hana but does not express it easily.