Female Room 8 The host of the game, Citizen. A female character with long hair wearing a pink beanie; she seems to have been quiet during her third year of middle school. However, one day she inherits her parents' company and becomes wealthy. She immediately drives a supercar to hold a reunion at the Deongdeuk Park campsite and suggests playing a Mafia game once night falls. Based on most of her dialogue after Episode 2, she appears to be quite emotionally fragile. She killed Koru in Episode 2.

Female Survivor Bacon's mother. In Episode 2, she hears the news about Bacon from Bay, who came to the basement room. At first, she doesn't believe him, saying Bacon is such a troublemaker that no one would kidnap him and he's not the type to get kidnapped, but she follows when she sees Bay getting into a police car. In Episode 3, 'Room of Faith, Night of Betrayal,' she witnesses Police Subordinate 1 being shot and killed by a masked figure and flees with Bay. In Episode 5, 'The Fissure Carved by Gunshots,' she flees with Bay, subdues an armed member of the host group without any equipment, and takes their gun. She then shoots a masked person passing by the bodies of the self-destructed police and tells Bay to run ahead while escaping from five armed thugs. She kills three of the thugs, excluding the two who went to catch Bay. Right after saying she needs to go find Bay, she is struck by Crow Mask's bat and knocked unconscious.

Female Room 3 Mafia A female character with gray hair. she is hostile toward her father, who abused her when she was young. When the family's situation became precarious because of her father, she tried to take a taxi to the reunion, but her father, claiming it was a waste of money, insisted on driving her himself. However, because it was an old car, a tire blew out, and she ended up walking to the reunion. Perhaps due to her family circumstances, she has a cold personality. Mentioning Luke in Episode 1 suggests something happened between them. She is revealed to be the Mafia in Episode 3, 'Room of Faith, Night of Betrayal,' and is effectively the female protagonist of this work. She killed Karu in Episode 3 and Rien in Episode 4. In Episode 6, 'In the Name of Brother,' she seems to realize Luke is a doctor, and she murders Luke in Episode 8.

Male Room 1 Police The undisputed protagonist of the work. While spending a boring weekend, he receives a call from Rachan, a middle school classmate. The call is an invitation to a reunion for their former classmates, and Bacon immediately steals Ammicon's car (...) to go to the reunion. His role in the Mafia game is the Police. He investigated Karu on the second night, but Karu was revealed to be a Citizen. In Episode 6, after comforting Rachan, he suspects Ruyo of being the Mafia.

Male Appears to hold a high rank. Serial number 1 in the Executor List. His codename is RCF. He is in charge of speaker recordings. He captures Ammicon and binds her arms with iron bars. At the end, he shoots and kills Sera's father. Crow Mask is actually Rachan's father. This is revealed when he kills Sera's father and says, "Rachan, this is your father's final revenge."

Soldier Mask Appears to have the lowest status among the host group. They are basic grunts equipped with guns who attempt to shoot and kill any intruders on sight.

Bat Mask When Bacon's friends gather to start the Mafia game, he suddenly intrudes, knocks everyone unconscious with a bat except for Bay, and drags them to the game location in a truck.

Sera's father. After his wife Erin became vegetative and died, he followed a friend's advice and squandered Erin's life insurance money, ruining the family's finances. In Episode 1, he drives Sera to the reunion in an old car, but gets cursed at by Sera when a tire blows out. According to facts revealed in Episode 7, he was a domestic abuser whose situation was severe enough that the police had already visited once. His abuse serves as the catalyst for Sera becoming violent later on. Because of this, the violent Sera ends up assaulting Rachan, which contributes to the opening of the Mafia game, making him the root of all evil in this work. However, judging by what he said while overcome with grief looking at Sera's funeral portrait in Episode 10, it seems he turned violent toward Sera after his mental state collapsed when Erin became vegetative. He eventually dies in front of his daughter's portrait after being shot by RCF.