Kamui Revelation Arc

Kamui Revelation Arc (神威啓示編,) is the eighth story arc in Bungo Stray Dogs and is the fifth story arc in the Decay of the Angel Saga. It focuses on discovering who the Decay of the Angel leader, Kamui is.

Synopsis
Atsushi declares that he knows the page's location through Sigma's ability and the page is currently held by the Decay of the Angel' leader, Kamui. Ranpo Edogawa sets out to meet Ōchi Fukuchi to ask for his help to clear the agency's name as terrorists.

Summary
Atsushi knows the pages' location through Sigma, which is currently being carried by Decay of the Angel's leader, Kamui. Atsushi reveals that to save the agency, they need to find and defeat Kamui and, currently, is carrying out an assassination plot on the agency.

Prologue
The plan for the explosive coin terrorism takes place. Jōno visits the detained Doppo Kunikida and offers for him to join the Hunting Dogs, to which Kunikida firmly refuses and tells Jōno to leave. Before leaving, Jōno reveals that Yosano's execution will occur that day, leading to Kunikida's remorse. Gogol saves the falling Sigma, which shocks Sigma considering that Gogol was to supposedly die during the hostage incident but reveals that Fyodor's words moved him and then decided to kill Fyodor to be free. He then asks for Sigma's help - to know Fyodor's ability using his ability. Meanwhile, at Anne's Room, Atsushi states that he knows the location of the page.

Ranpo's Rescue
During his isolation, a sniper targets Kunikida. A masked man who reveals himself to be Kamui captures the unconscious Kunikida. Meanwhile, Yosano is currently on transport for condemned criminals. During the way, an explosion occurs before them, causing the transport vehicle to stop for a while. When the military police return, they find the vehicle and Yosano gone. Katai, who is currently guarded on his apartment, vanishes as soon as he opens a smartphone sent by someone from the outside. Fukuzawa is taken for interrogation by two men and is brought to the rooftop of a building.

The masked man is revealed to be Ranpo, who all taken the agency members to safety. He reveals that during the hostage crisis, the police have surrounded him, and he can escape from the dragnet. He since then done investigations and uncovered the enemy's assassination plot against the agency, hence saving the other agency members. He reveals his methods on how he saves Kunikida and Yosano. For Katai's rescue, he got help from a friend, which revealed to be Poe using his ability to let Katai evacuate.

Fukuzawa then gives orders to Ranpo to destroy the case.

Ranpo's Broadcast and Arrest
During a press conference, Ranpo makes his appearance. The people inside the conference room panic at the sight of the terrorist. A female reporter asks Ranpo why they have plotted all the terrorist attacks. Ranpo proceeds to show them the video footage of the hostages, which was sent to the agency. He reveals that the agency had come to rescue the hostages only to be framed as terrorists. However, he wasn't believed by the reporters, knowing that those aren't the facts they know. He shows them the evidence he compiled proving that the agency is not terrorists, but the evidence is suddenly disposed of. He further reveals that a certain page alters the reality making the agency a terrorist.

Shortly after, the military police appeared. Before getting arrested, he gives a final message to the police, offers to think with their soul, not job nor position, and tells them that a master detective himself would never make a basic mistake such as letting himself get on a wanted list. The police then take him away.

During Ranpo's transfer arrest, he is saved by Minoura. The police force has been divided - causing the other police forces to protect Ranpo. As a result, Ranpo manages to run away with Minoura's help. Soon after, Ranpo, with Yosano, Kunikida, and Katai, rejoins Atsushi and Kyōka. Ranpo states that since most of the agency members have already gathered, he must contact someone.

United Nations Beseechment
At his office, Ōchi Fukuchi is approached by the United Nations' Counter-Terrorism Committee about creating an anti-terror group that will counter the terrorists and lead it. During the U.N.'s proposal, Fukuchi demands to change the UN's assumptions that the agency is the terrorists and he can accept their offer.

At the U.N. special headquarters located inside the Standard Island, delegates of the U.N. are seen concluding a meeting about the Supernational Armed Security Force, the anti-terror army. Before the councilmen vote on whether to support the idea or not, Fukuchi makes his presence known.

Fukuchi starts his speech by saying that they are already losing the war against the terrorists. To fight against the new era of terror, Fukuchi states that they must abandon multinational forces altogether and adopt a pan-human defense force that will command all the world's armed forces and be permitted to enter independent zones. Before leaving, he concludes his speech by calling the anti-terror group to be the army of mankind and strongly asks the councilmen to vote in favor of the draft resolution.

Agency's Seek for Assistance
After Fukuchi's speech, he is greeted by Ranpo. During their conversation, Ranpo reveals that Fukuzawa had ordered him to see Fukuchi and tells their plan to team up with the Hunting Dogs to defeat the Decay of the Angel. After some negotiation and persistence, Fukuchi agrees to help the agency due to Ranpo and Fukuzawa's belief in him. They soon meet up with Atsushi, disguised as a ship worker and waiting at the Boswellian.

Fukuchi orders the two to wait out the security in the U.N. ambassador cabins until they reach the port from the Yokohama coast. While hiding out, Ranpo begins to deduce the true identity of Kamui. Using the information he has gathered, Ranpo finds the true identity of Kamui, which is revealed to be Ōchi Fukuchi.

When he learns the truth, Ranpo sends a signal flare and apologizes to Atsushi. Shortly after, Fukuchi attacks him from behind and saves Atsushi, but Ranpo can transport himself in Poe's novel just in time. Before disappearing, Ranpo attempts to inform Atsushi about Kamui's ability but isn't able to properly deliver the message as he has already been transported into the novel.

Battle with Kamui
Atsushi stands before Fukuchi with no allies around him. Just then, Akutagawa arrives at Atsushi's aid as per Dazai's orders. Atsushi and Akutagawa soon face Fukuchi together in a battle. However, even though Akutagawa and Atsushi combine their power and skills, they are still overpowered by Fukuchi's ability and equipped weapon. Towards the end of the battle, Fukuchi invites Akutagawa to train under him as a member of the Hunting Dogs and orders to kill Atsushi. During the event, Akutagawa also reveals that he won't be able to live much longer due to his lung disease, indicating that he cannot disappoint Dazai with the time left. Agreeing to Fukuchi's invitation and order to kill Atsushi, Akutagawa uses the opportunity to charge toward Atsushi to trick Fukuchi and uses the opening to activate Beast Beneath the Moonlight–Rashōmon: Black Tiger's Supreme Claw, which allows Atsushi to sever both of Fukuchi's arms.

However, Fukuchi changes the outcome of events allowing him to sever Atsushi's arm and slash Akutagawa instead, which he reveals is the power of his sword that can cut through time and space. Fukuchi fully uses the sword's power to once again anticipate Akutagawa's misdirection attack before their escape which eventually results to Atsushi and Akutagawa's defeat, which also left Akutagawa dead.

Impact

 * The United Nations is forming an anti-terror group, the Supernational Armed Security Force.
 * Kamui's true identity is revealed to be Ōchi Fukuchi, the captain of the Hunting Dogs.
 * The fifth and last member of the Decay of the Angel is revealed to be Bram Stoker, a vampire.
 * Akutagawa's lifespan reveals to be limited due to his lung disease.
 * Akutagawa, Higuchi, Gin, Hirotsu, and other mafiosi have turned into vampires starting a vampire outbreak.