Name: Bong Dojin Age: 32 Gender: Male Occupation: Firefighter (Fire Suppression) Relationships: Bong Anna (Younger sister), Dokgo Soon (Senior), Song Seol (Crush), Ha Dongwoo, Choi Gisu, Song Seol (Juniors) Traits: A firefighter at Seoul Taewon Fire Station. He deeply cares for his nozzle assistant, Gisu. He is nicknamed "Bulldozer" because he charges into fires carrying 20kg of equipment. Fire is what he fears most, yet what he isn't afraid of; it's what he loves, hates, and knows best, which is why he also serves as a fire investigator. Despite his terrifying strength and stamina, he is usually a kind senior who takes good care of his juniors. In the past, he caused a fire at Kang Doha's birthday party, leaving Doha with traumatic burns. This incident likely led him to become a firefighter. He received a scout offer from Yoon Hong but declined, saying firefighting suits him better. He usually drives the pump truck but sometimes lets Gisu take over while he drives the ambulance. He is nicknamed "Chef Bong" because he handles the cooking at the station cafeteria.

Name: Ha Dongwoo Age: 26 Gender: Male Occupation: Firefighter (EMT) Relationships: Dokgo Soon, Song Seol, Bong Dojin, Choi Gisu (Seniors) Traits: An EMT at Seoul Taewon Fire Station. He worries about and respects his ambulance partner, Song Seol. Aside from the newly recruited firefighters, he is the junior to almost everyone at the station. As an EMT, he spends a lot of time in the ambulance. He is prone to tears but remains fairly realistic. While his emergency medical skills are good, they aren't as sharp as Seol's. Therefore, he deeply respects and learns from Seol, who has extensive experience as a nurse and in surgeries.

Name: Choi Gisu Age: 31 Gender: Male Occupation: Firefighter (Nozzle Assistant & Rescue Squad) Relationships: Dokgo Soon, Bong Dojin (Seniors), Song Seol, Ha Dongwoo (Juniors) Traits: A rescue squad member and fire nozzle assistant at Seoul Taewon Fire Station. He serves as Dojin's nozzle assistant while also working on the rescue team. He has a solid, muscular build and a rugged appearance, but he is more soft-hearted than anyone. He trusts and follows Dojin like an older brother.

Name: Dokgo Soon Age: 45 Gender: Female Occupation: Firefighter (Field Command Chief) Relationships: Bong Dojin, Choi Gisu, Song Seol, Ha Dongwoo (Juniors) Traits: The Field Command Chief at Seoul Taewon Fire Station. As befits her rank, she directs the station family at the scene. She was the first female fire suppression officer. She intentionally pushes the crew hard and scolds them until they cry for even small mistakes, but in reality, she loves and cares for her team more than anyone else.

Name: Jin Hogae Age: 35 Gender: Male Occupation: Police (Detective) Relationships: Song Seol (Crush), Baek Cham (Senior), Gong Myeongpil, Bong Anna (Colleagues) Traits: A detective in the Violent Crimes Unit at Seoul Taewon Police Station. A "crazy" detective with a 118% arrest rate. He has an incredible nose for cases and will dive into anything related to an investigation regardless of the danger. For this reason, his nicknames are Mut, Jindo Dog, and Mad Dog. He has a crush on Seol but doesn't show it.

Name: Gong Myeongpil Age: 32 Gender: Male Occupation: Police (Detective) Relationships: Baek Cham (Senior), Jin Hogae, Bong Anna (Colleagues) Traits: A corporal in the Violent Crimes Unit at Seoul Taewon Police Station. He is Jin Hogae's partner, and they have great chemistry, constantly bickering and joking around. They are an irreplaceable, fun duo. He was already acquainted with Song Seol, so he treats her comfortably. He is also friendly with the rest of the fire station crew and jokes with them. He often goes to the house next door with Anna to get a free meal.

Name: Baek Cham Age: 47 Gender: Male Occupation: Police (Detective Team Leader) Relationships: Jin Hogae, Gong Myeongpil, Bong Anna (Juniors), Dokgo Soon (Spouse) Traits: The captain of the Violent Crimes Unit at Seoul Taewon Police Station. He has a bit of an "old school" vibe but is kind and worries deeply about his team. He is married to Dokgo Soon from the fire station.

Name: Bong Anna Age: 27 Gender: Female Occupation: Police (Forensic Investigator) Relationships: Bong Dojin (Older brother), Baek Cham (Senior), Jin Hogae, Gong Myeongpil (Colleagues) Traits: A forensic investigator at Seoul Taewon Police Station. Despite her young age, she is incredibly smart; hacking is basic for her, and she is so good at her job that Dojin often uses the "family card" to ask for her help when he needs it. She is also very close with Seol.

Name: Yoon Hong Age: 35 Gender: Female Occupation: NFS (Medical Examiner at National Forensic Service) Relationships: Kang Doha (Best friend), Bong Dojin (Crush?) Traits: A medical examiner at the Seoul National Forensic Service. A girl-crush, workaholic female medical examiner. She usually has a cool and refreshing personality, but she gets annoyed if anyone interferes with an autopsy. She is realistic and speaks only blunt facts, but she also has a kind and warm side at times. She has been best friends with Kang Doha since their study abroad days in the US. She has a slight crush on firefighter Bong Dojin and wants to recruit him to her NFS team, but Dojin refuses.

Name: Kang Doha Age: 35 Gender: Male Occupation: NFS (Forensic Engineering at National Forensic Service) Relationships: Yoon Hong (Best friend), Bong Dojin (Close friend) Traits: A member of the Forensic Engineering Department at the Seoul National Forensic Service. He was previously a captain in the Air Force EOD (Explosive Ordnance Disposal) unit. While playing with Bong Dojin as a child, Dojin caused an accident that resulted in a fire, leaving Doha with burns and an indelible scar. His personality is just as eccentric as Hogae's, earning him the nickname "Kang Psycho." As a side note, he has a history of accidentally setting off a bomb while trying to defuse it. Perhaps because of that, when cutting wires to defuse a bomb, he often asks, "What color do you like?""}],