Duel Noir

Duel Noir is a killing game featured in Danganronpa Kirigiri. It was created and hosted by the Victim's Catharsis Committee as a way for victims of crimes to receive 'Catharsis' against the one responsible for ruining their life that had not been brought to justice either because the culprit was never found, the wrong person was arrested or they were never punished for their crime.

Overview
A Duel Noir generally involves four parties: The Culprit, The Detective, The Target, and the Innocent. When accepting The Duel Noir, the Culprit has to assemble a 'deck' first. This is done by 'renting' Techniques to use by the Committee, Techniques that can not be traced by any means. These Techniques range from murder weapons like poison or a baseball bat to tricks to assist them in the Duel Noir like, for example, hidden rooms, and, finally, the location on where it is held. Every Technique has a price assigned to them.

The Culprit can invite other Innocents unrelated to the crime against them, who they can frame, kill, or do anything freely, but there is no benefit or setback for doing so. Once their 'deck' is complete, a letter will be sent to the Detective. This letter has an electromagnetic lock which, once opened, will automatically start the Duel Noir. The Detective is always chosen from the Detective Library and their quality is decided based on the price of the Culprit's 'deck'. For example, going for a cheap 'deck' will result in a poor Detective and vice versa.

In order for the Culprit to win, they have to kill their Target and for seven-days not get found out by the Detective who they are not allowed to kill. Upon completion, they will gain 'Catharsis' and receive the amount of money their 'deck' was worth with the added options to start life under a different name and different country. As a result, a Culprit might be inclined to risk the Duel Noir against a good Detective for high monetary gain. If the Culprit is found out by the Detective or if the Detective dies, then they immediately lose and the Committee will cut ties with them, leaving them to face the law, in some cases. Besides, they will have to pay the Committee the money they used to purchase their 'deck'. If the Culprit can't pay, they will be executed.

According to Tōkichirō Endō a Duel Noir has a 70% chance of success in favor of the Culprit, and there have been cases of the Detectives not even showing up to stop them, thinking it was probably a prank.

Sirius Astronomical Observatory Murder Case
The Sirius Astronomical Observatory Murder Case is hosted by Tadashi Asakura and Tōkichirō Endō who are responsible for the murders that occurred inside the Sirius Astronomical Observatory. Tadashi first meets Tōkichirō in a park who tells him about the organization and then says that he will reveal to him the identity of the real criminal of the one who murdered his family under one condition. Tokichiro begins to tell him about Catharsis and, to get it, he must play a game called Duel Noir, along the way telling him different rules. Having finished with all the rules, Tokichiro says that he cannot tell him who the criminal is, until he agrees to participate in the game and gives him one night to think it over and asks him to come to the park at ten o'clock in the morning. Tadashi says goodbye to the old man.

Five detectives are summoned to solve a case located on the Sirius Observatory who all first arrive at Hatesaki Station. Yui Samidare (DSC 888), Kyoko Kirigiri (DSC 919), Eigo Amino (DSC 367), "Shīta Enbi", and Kō Inuzuka (DSC 943)—were the detectives who were called to the case. The Detective group later arrived at the Sirius Astronomical Observatory and started to investigate the building and its furnishings. However, Yui along with the other detectives was tricked as the client never showed up, but instead, they ended up in another situation.

Later when Yui and Kyoko woke up, together they investigate the mystery surrounded the Observatory. The culprit, Tadashi is later revealed when he surrenders in front of Yui and Kyoko after the latter threatens to burn the building to the ground, to which they find him hiding in a small chair. Yui asks him who he is, to which he replies that his name is Tadashi Asakura. Tadashi confesses that he killed three people and lost, and later says that he sent an order on behalf of Ooe Yoshizono to five detectives to collect them in this place. He also adds that in Shita's letter, he indicated the time of gathering a little earlier to call him in advance before he killed, dismembered, and hid him in the telescopes and the chair, while he pretended all this time to be Shita and did not let anyone go to the telescopes. Tadashi was surprised that a novice detective like Kyoko was able to defeat him and asked her when she first noticed that the chair in which she sat, hid him, to which she says that this was part of her analysis from the very beginning.

Norman's Hotel Murder Case
Once Tadashi was arrested, Yui, Kyoko, Suisei Nanamura, and other detectives were summoned to participate in the Norman's Hotel Case. Everyone meets at the front door of the hotel when they open the thick double doors to find a small room inside with another set of double doors. They open this to enter the hotel lobby, which seemed to be as wide as a gymnasium. The detectives unaware at first, get trapped inside the hotel, they meet seven people inside the lobby, Yuzen Minase, Akio Chage, Meruko Mifune, Mikado Shinsen, Sae Yozuru, Taehime Uozumi, and Seiunsai Toyano'oh. Yui and Kyoko introduce themselves to everyone that they are detectives who have come to capture a criminal, leaving out details about the Duel Noir and the Committee. Instead, she tells them that they received a notice that a murder was about to take place between the space of today and New Year's Day. Suisei decides to wait until 6 p.m. to come around and see what this auction is about.

Inside the Hotel, a microphonic voice suddenly speaks up. This voice came from a portrait and the boy's portrait mouth seemed to be able to move. In that microphonic voice, he introduces himself as Norman and his position of being a serial killer who died a century ago. Norman starts to tell them to take their seats at the dining table to begin his explanation. When everyone takes their seat, starts to tell everyone to empty their pockets and put all the money they had on the center of the dining table, due to the money not being eligible for the auction. Norman also asks everyone to body check the people on their left to prevent any cheating. Taehime afterward is ordered by Norman to collect all of the money on the table and throw it into the fireplace. Norman tells them not to fret, and to stretch their legs under the table. There they find heavy knapsacks, which they pull out. Each knapsack contains 100 million yen. Norman explains to them the rules of the Duel Noir rules. An auction every day will be hosted at 6 p.m. Since the time limit of the Duel Noir is until January 1st at 10 a.m., that means the auction will be held five times at most. No one will be able to leave the auction house until the auction is over. Also, there will be only one item, the same item, put up for sale at each auction. That way, if they miss buying it at one auction, they would have the chance to get it next auction. That item is “the Right of Detective”— the right for whoever has it to be a detective.

During the events of the auction, everyone was getting killed by a mysterious murderer, with only some people remaining including Yui, Kyoko, and Suisei. Suisei attempts to murder everyone with a revolver to take all the money in the house for himself. Suisei attempted this to not make him a suspicious culprit if there were no witnesses, Suisei approached Yui and Kyoko in an attempt to murder both of them. However, Suisei was willing to let Kyoko live if she didn't tell anyone, but to Suisei's disappointment, Kyoko decides to be on Yui's side no matter what. However, Meruko who was shot earlier appears to be still alive against all odds and it's heavily implied that she used her psychic abilities to prevent Suisei's gun from firing, ultimately saving Kyoko and Yui's lives as she managed to distract Suisei long enough for the entrance hall doors' opening time. On their way out, Yui and Kyoko encountered Mikado Shinsen. Besides Mikado, two other participants were also found behind him. Yui and Kyoko had discovered Mikado's true identity during the events. Suisei later commits suicide by shooting himself in the head. They found out that he was the head of the "Victims Catharsis Committee", standing behind the Duel Noirs, and a rogue master detective on par with Fuhito in terms of Detective work and was possibly a rank 000 detective.

Trivia

 * This is so far the Killing Game with most participants and one of the only ones without any Ultimate Students from Hope's Peak Academy.