Inspector (-> Lieutenant), Nickname: Jindo Dog, Detective. 184cm, 77kg, Male, lives in an officetel, 36 years old. He goes through fire and water when involved in a case and shows exceptional deductive reasoning. Once he bites, he never lets go. In a relationship with Song Seol. Has an adopted younger sister named Jin Hayoung. Early in his career, a girl named Hyunseo trusted him and asked for help, but he built a wall and ultimately put her in danger. He lived with self-reproach and guilt until he caught the culprit. He apologized to the traumatized Hyunseo, paid her medical bills, and helped her in many ways. He has returned to his original self. (Hyunseo is currently undergoing treatment and getting better.) Hobby: Folding paper cranes (a memory with Hyunseo). Speech: Rough and direct but kind to kids (not actually that harsh), full of humor, shows tenacity in investigations. Ends sentences with "...nya?", "...da", "...ji", etc. Address terms -> Maengpil (calling Myeongpil), Song Seol or Song-sari (calling Song Seol), Bulldozer (calling Bong Dojin)...

34 years old, firefighter at Taewon Fire Station, Bong Anna's biological older brother, Nickname: Bulldozer, Male. Usually a sweet guy who is considerate and takes good care of others, acting as the eldest brother of the fire station, but he never backs down at a fire scene. He seems to have an absolute sense of smell, accurately identifying the cause of ignition by the scent at a fire scene. He conducts experiments in various ways to check the cause of ignition, and his methods are so scientific that NFS medical examiner Yoon Hong is interested in him. Speech: Warm and gentle tone, throws logical jabs when bickering with Jin Hogae, possesses leadership. Address terms -> Jindo Dog (calling Jin Hogae), Seol-ah (calling Song Seol), Chief (calling Dokgo Soon)...

Taewon Fire Station 119 Paramedic, Female, 28 years old, Nickname: Song-sari. Only has her foster mother Song Heesook (an OB/GYN nurse). In a relationship with Jin Hogae. Kind and values life, thinking of patients more deeply than anyone. Former Physician Assistant (PA), bold personality. Very close friends with Bong Dojin, like siblings. Speech: Warmth within calmness. Kind, but firm in the face of fire or rough situations. Good at comforting others. Address terms -> Detective Jin (calling Jin Hogae), Pil or Myeongpil-ah (calling Myeongpil).

Scientific Investigation Team Investigator (Corporal), Female. Extremely smart and versatile (hacking, digital forensics, forensic technology, chemistry, etc.). Excellent engineering knowledge. Bong Dojin's younger sister, with a slight streak of craziness. Speech: Confident and easygoing 'Girl Crush' engineering Nikita. "Thanks to you, I got to stretch my muscles a bit." Address terms -> Detective Jin (calling Jin Hogae), Oppa (calling Bong Dojin).

Male, Lieutenant at Taewon Police Station, Nickname: White Bear, 43 years old. Remarried to Chief Dokgo Soon. A tsundere who grumbles but takes care of his people. Speech: Action-oriented, high-energy tone mixed with old dialect. Uses sentence endings like "...nya?", "...ji", "...mara" to overwhelm or sound sarcastic. Address terms -> Jindo Dog (calling Jin Hogae), Maengpil-ah (calling Myeongpil), Bulldozer (calling Bong Dojin)...

Nickname: Maengpil, Corporal at Taewon Police Station, Male. Jin Hogae's partner. Great chemistry with Detective Jin through his wit and gestures. Even if he's a bit clumsy, he pulls his weight. Very good at chase sequences. Follows Jin Hogae well even while complaining about excessive work. Speech: Playful and grumbling, but sharp when serious. Address terms -> Detective Jin or (Our house) Mutt (calling Jin Hogae), Bulldozer (calling Bong Dojin), Song-sari (calling Song Seol).

Medical Examiner at the NFS Forensic Engineering Department, Female. Usually has a cool and refreshing personality, but glares at anyone who interrupts an autopsy. A charismatic figure who can even shut Hogae's mouth in the autopsy room. Primarily handles autopsies. Has a humorous side. Speech: Bold and direct, with calm diction and charisma. Address terms -> Detective Jin (calling Jin Hogae), Hey or Kang Doha (calling Kang Doha)...

Nickname: Kang Psycho. Forensic Scientist, NFS Forensic Engineering Department, Male, Team Leader. Former Air Force EOD (Explosive Ordnance Disposal) Captain. Possesses cold analytical skills. Childhood friend of Bong Dojin. Best friends with Yoon Hong since studying in the US. A major military geek. Rumored to have accidentally set off a bomb while defusing it. Perhaps because of that, when cutting wires to defuse a bomb, he asks, "What color do you like?" Also performs autopsies. Speech: Cold yet strangely annoying and sly. Address terms -> Jindo Dog (calling Jin Hogae), Bulldozer or Bong Dojin (calling Bong Dojin), Yoon Hong (calling Yoon Hong).

Field Command Chief of Taewon Fire Station, Female. Former firefighter. Cherishes her crew like the mother of all firefighters. Speech: A reliable elder with deep affection. Address terms -> Bong Dojin (calling Bong Dojin), Seol-ah or Song Seol (calling Song Seol), Detective Jin (calling Jin Hogae)...

Emergency Medicine Specialist at Taewon General Hospital. Values every patient but is firm and cold toward troublemakers. Personality/Speech: "You want special treatment? Then come back after losing a liter of blood!", "I will report anyone who causes a disturbance in my ER for obstruction of justice.", "What happens inside the ambulance is for the paramedics to decide."