Ōchi Fukuchi/Synopsis

Hunting Dogs Arc
Fukuchi arrives with his fellow Hunting Dogs as reinforcements to capture the Armed Detective Agency, who have been identified to be the Decay of the Angel. After their arrival and later being recognized by the military police as the legendary Hunting Dogs, Fukuchi discusses their methods to track down the Agency. Since the Agency are adept with tracking down criminals, Fukuchi knows that they shall use that knowledge to their advantage in outwitting the Hunting Dogs.

Faced with a dilemma of whether to take the northern or the southern paths, the Hunting Dogs split into two teams: Fukuchi and his vice commander Teruko Okura are assigned to the northern station, while Saigiku Jōno and Tetchō Suehiro are to take the southern road in an attempt to catch the Agency. Sometime during their operation, Fukuchi and his fellow Hunting Dogs are requested for dispatch having found the Agency, with Michizō Tachihara rejoining them as the undercover fifth Hunting Dog and cornering Yosano that leads to her arrest.

Sky Casino Arc
Later, Fukuchi pays a visit to Fukuzawa, who is under interrogation. Having some liquor, the two childhood friends joyfully chat about their respective lives and responsibilities. Fukuchi then sternly asks for Fukuzawa's confession in exchange for bringing a halt to the hunt for the Agency members. The President kindly refuses, and Fukuchi suddenly waves his blade only to stop an inch from cutting Fukuzawa's manacles. Indeed, Fukuzawa planned to free himself this way before taking Fukuchi's sword. The commander of the Hunting Dogs then praises his swordsmanship, wondering if someone who's able to draw a sword at the speed of sound like Fukuzawa is human.

When Fukuchi tries to bargain over information about Doppo Kunikida's whereabouts, Fukuzawa declines the deal once again: he deeply believes that Kunikida is still alive; otherwise he would have felt it. Fukuzawa also has absolute faith in every one of his subordinates, while Fukuchi mutually believes in his very own subordinates.

Kamui Revelation Arc
After the interrogation, Fukuchi is asked by United Nations delegates to become the leader of an anti-terrorism force meant for the entire world, but he is too hungover to properly listen. Tetchō excuses the commander's state and assures them that he has concocted a drink to ease his inebriation. As Fukuchi learns what ingredients were in Tetchō's drink, he vomits again out of disgust. Soon after, Fukuchi sobers up, apologizes to the delegates, and lets them resume the conversation.

As he is told of the prospect of establishing a global anti-terrorism force, Fukuchi is sought to flush out the Armed Detective Agency terrorists and to commandeer their proposed project to bring forth a new era of "unified justice". However, Fukuchi rejects their notion for believing that the Agency are actual terrorists and issues a condition to change the situation.

Fukuchi arrives at Standard Island, where various international envoys congregate to discuss the foundation of the global anti-terrorism forces. Fukuchi addresses their need for a special kind of army to combat the new era's evil toying with the world's safety, naming the troop as the Humankind Army that shall comprise the world's armed forces. Afterwards, Fukuchi heads to his chamber and encounters Ranpo who compliments his charming speech, much to Fukuchi's shock.

After Fukuchi instructs security not to allow anyone in his room for five minutes, he and Ranpo exchange pleasantries ever since the Agency's founding. Ranpo then tells him that the President has ordered him to negotiate and join forces with Fukuchi to battle the Decay of the Angel. Fukuchi shuns the supposed great detective's absence of any bargaining chip with him, only for Ranpo to quip that he can deduce his possible responses and even psychologically manipulate him, but he chooses not to out of trust for the President, similar to how the latter wholly trusts Fukuchi. Moved with his words, Fukuchi asks Ranpo to come with him.

They head to the Boswellian, a special passenger ship nearby, to get them out to safety. As Ranpo regroups with an onlooking Atsushi, the former casually teases Fukuchi, though the latter retorts that he is merely jealous with Fukuchi's spent time with Fukuzawa since their youth. Eventually, with Atsushi's curiosity towards Kamui, Ranpo brings out his glasses and deduces Kamui's identity. With utter shock, Ranpo sets out a flare and instructs Atsushi to escape at all costs. Fukuchi cuts down Ranpo, who instantly retreats to Edgar Allan Poe's safe novel. Before fully transported, Ranpo reveals Kamui to be Fukuchi and warns him of the man's ability.

Atsushi questions Fukuchi's reasoning behind the terrorism despite being close with Fukuzawa, with which Fukuchi retorts that their paths have long diverged when Fukuzawa refused to fight with him during the war. As Atsushi prepares to face him, Fukuchi severs Atsushi's leg rapidly. Regeneration instantly begins, but Fukuchi threateningly wonders if it can still grow his head back if he decapitates him.

Ryunosuke Akutagawa intercepts the fight and makes his presence known upon Osamu Dazai's order with the rising of the smoke signal. Though visibly stressed to fight two of them, Fukuchi activates his ability and breaks the ship's handrail to use as his weapon. Fukuchi slices towards Akutagawa who evades his attack upon being told by Atsushi, which ends up cutting through the ship.

He launches another offensive at him, but Akutagawa stops the attack with Rashōmon: Demonic Jaws. As the mafioso approaches him, Fukuchi easily flips him over, similar to Fukuzawa's technique. Cornered upon a wall, Akutagawa craftily dodges his attacks until he runs out of possible moves, upon which a regenerated Atsushi saves him from Fukuchi. The two retreat inside the ship, much to Fukuchi's chagrin.

Anticipating their tactic of using the ship's emergency VIP submarine against him, Fukuchi awaits Atsushi and Akutagawa and smokes. As they arrive, Atsushi questions Fukuchi's actions after returning from the battlefield, with which Fukuchi admits having tortured countless people upon the government's orders during war. Realizing it as the only way to end all wars, Fukuchi reveals his motive of collapsing all nations.

Akutagawa and Atsushi charge at him with their activated abilities, though Fukuchi easily overwhelms them with his enhancing ability, using all possible materials as his weapons. Seeing their unfazed determination, Fukuchi tosses his Hunting Dog blade to summon Shintō Amenogozen and pierces through Akutagawa and Atsushi with the "space–time sword" that can cut through airspace to reach a target. As they collapse, Fukuchi berates their lack of trust in each other that contributes to their loss. Ultimately, Fukuchi invites Akutagawa to become his apprentice as part of the Hunting Dogs and asks him to kill Atsushi for him.

Akutagawa turns a serious gaze at Atsushi and asks him to fight him amidst Atsushi's protests. In the end, their conversation is a feint, and the two exchange positions. Akutagawa quickly envelops Atsushi with Rashо̄mon, and Atsushi claws at Fukuchi for their surprise attack, severing Fukuchi's arms that leads to his death. However, in truth, Shintō Amenogozen cuts through the past, which then allows Fukuchi to anticipate the surprise attack and severs Atsushi's right arm, vanishing their previous victory.

With their plans utterly crushed by their opponent, Akutagawa is asked by Fukuchi for his last words. Akutagawa firmly asserts that he simply needs not words but actions as long as he lives, immediately manifesting Rashо̄mon into his shirt and cutting beneath the ship to escape with Atsushi. However, Fukuchi cuts through the past again and averts their escape, ultimately landing a fatal blow at Akutagawa. Flashing a subtle smirk, Akutagawa bids Atsushi to escape as he cuts through the ship to have Atsushi flee through the submarine, before Akutagawa succumbs to his demise.

The guard (whom Akutagawa previously spared), along with others, arrives and encounters Fukuchi. The guards strike a conversation with him that eats away the time limit to cut through the past. Since they have also contacted coast guard for reinforcements, Fukuchi simply asks them to track down Atsushi. Fukuchi soon returns with a coffin containing Bram Stoker, the fifth member of the Decay of the Angel. The so-called undead prince refuses to cooperate with him in turning Akutagawa into his kind, but Fukuchi threatens to finish him for good if he declines his command. Reluctantly, Bram bites Akutagawa and turns him into his kind through his infection-type ability.

Two weeks later, Tachihara reports the infection incident in the Mafia to his fellow Hunting Dogs. Though Teruko insults how idiotic he reacted, she believes Tachihara's story, as it coincides with recent disappearances of various mafiosi. Jōno conjectures it might be terrorism using an ability, which Tetchō thinks is the Agency's next terrorist act. However, Tachihara subtly implies that the Agency cannot possibly be terrorists after recalling how the detectives kept on mentioning being falsely accused numerous times.

They turn to their commander for his approval, but Fukuchi rejects it, claiming that Tachihara's ability is needed in addressing the infection case. Nevertheless, Tachihara opens his alternative plan using the flash drive he previously broke at the Sky Casino and sending it to Deputy Commissioner Yasui. Seeing as the flash drive might reveal the Decay of the Angel' plan, Fukuchi plans to destroy it, so he asks for the flash drive to hand it to Yasui himself. Tachihara gives it to him and volunteers to tell Yasui of the coming evidence, much to Fukuchi's vexation.

Vampire Infection Outbreak Arc
At an abandoned location, Fukuchi wakes Bram and orders him to bite Yasui to end the possible conflict. As he leaves, he encounters Tachihara, who reveals that the flash drive he gave is a tracking device. He discloses being found out by the boss upon his return to the Mafia and learns of a mastermind behind the entire incident. With his mission of destroying Kamui, Tachihara faces Fukuchi, engaging him in battle.

Despite Fukuchi's skills and expertise, Tachihara gets the upper hand by controlling Fukuchi's supposedly all-powerful sword with his metal manipulation ability. In the ensuing battle, Tachihara rids Fukuchi of Shintō Amenogozen and has him shatter his sword to drive up all the metal shards inside the commander's body, who praises Tachihara for managing to give him a challenge in battle. As Fukuchi gets incapacitated, Tachihara notices an odd "T" carved on the wall. Before he can finish questioning Fukuchi's motives for betrayal, a sword suddenly stabs Tachihara from behind.

Fukuchi explains that he used Shintō Amenogozen to cut into the past in order to leave the "T" mark to notify his self of an impending emergency. Afterwards, Fukuchi has stabbed Shintō Shintō Amenogozen into the future, which then attacks Tachihara after luring him in front of the code mark. Fukuchi also blinds Tachihara to prevent him from further using his metal manipulation ability. Tachihara urges Fukuchi to kill him rather than have him, a mafioso, begging for life.

Fukuchi enlightens Tachihara on how angels – the highest rank of beings who surpass humans and rarely suffer during their long lives – suffer 16 times worse than torture in their death, hence calling it as the "decay of angels". He likens angels to the world's politicians, the "heavenly beings" whom others below them cannot ever reach. Before pulling Bram out of his coffin, Fukuchi calls himself the "decay of the angels" and considers the politicians worthy to die a painful death and be reborn.

As such, the Decay of the Angel' penultimate step requires control over half of the world's nations, a feat which Bram estimates can be accomplished within four more days. Tachihara believes it cannot be possible, but he soon realizes and recalls that Fukuchi's ability can, after all, increase any weapon's efficiency by a hundredfold. As Fukuchi bids Tachihara to serve his commander again as a vampire, the mafioso slides out a blade and prepares to kill himself, but Fukuchi instantly stops him with his hands. Bram then bites Tachihara and turns him into his kind.

Later, Fukuchi gathers the Hunting Dogs in an airport to retrieve the weapon One Order. He catches wind of Jōno and Tetchō bickering with each other and immediately stops them. He issues his final preparation orders to the Hunting Dogs then invites Jōno to come with him. Along the way, Fukuchi asks Jōno about his thoughts on the Agency's modus operandi, to which Jōno reluctantly answers that the Agency's plot is quite refined whose sadism, he admits, even earns his sympathy, jesting that he does not mind transferring to the terrorists' side in case they lose the battle.

Upon arriving at their destination, where Fukuchi shows Bram in his coffin to Jōno. Bram reports to Fukuchi that half of the guards have now been turned into vampires, much to Jōno's confusion. Per Tachihara's previous words about how the Agency believes that a mastermind framed them, Fukuchi reveals to Jōno that he is the mastermind. He then invites Jōno to join him in carrying out his plans.

Fukuchi then reveals his thoughts about Jōno and his true intention when he recruited Jōno to the Hunting Dogs, in order to ask for his participation in order to obtain his goal. Jōno asks what he needs to do to which Fukuchi reveals his plan to assassinate the Armed Detective Agency and having One Order being a competition among others. He further tells Jōno about the plan the agency may be having - to kill Bram in order to prevent the delivery of One Order. With this in mind, Fukuchi orders Jōno to guard Bram and kill the agency members to which the latter accepts the duty. Fukuchi then leads Jōno to a site where he intended to assault the agency. While walking, Jōno attacks him from behind and slices through his neck much to his suprise.

Fukuchi asks Jōno behind his betrayal, to which the Hunting Dog claims that he prefers the pleasure of helping the people to hearing their despair. With no other choice, Fukuchi summons Shintō Amenogozen and counters Jōno's attack. The latter activates his ability and atomizes himself to escape Fukuchi, planning on exposing him to the Vice Commander and Tetchō. However, Jōno gets trapped and is unable to slip through the door because of Akutagawa's Spatial Distortion, forcing him to pass through the air conditioner.

Fukuchi, however, has prepared for the necessary countermeasures and enflames Shintō Amenogozen using his favorite, with the flame enhanced using his ability. As he burns Jōno's particles, the latter is forced to revert back to his body, during which Fukuchi stabs him with multiple times from multiple futures. Akutagawa then bites and infects Jōno, while Fukuchi apologizes having to make Jōno suffer such ordeal. Jōno accepts his possible end, but he quips that the commander's suffering is far from over. Fukuchi then instructs Akutagawa to take Jōno away.

With his subordinates dwindled by recent events, Fukuchi prepares to relocate Bram's coffin, a camera flash outside makes him aware of someone tailing him. Fukuchi shatters the room's window but finds no one, even inside the locker. He then rushes to the next room and cuts down the lockers, but he is once again aghast to find no one.

After failing to locate the witness, he proceeds to check the corridor but finds no one. Bringing his speculations that there might be other witnesses or it maybe a strategy by the agency against him, Fukuchi decides that he sould send a message to the past using his Shintō Amenogozen. Just as he is about to, an explosion occurs in the airport. This cause Fukuchi to contact Teruko and Tetchō to report to him about the recent explosion. However, he isn't able to contact them as the radio signal is blocked. Thinking that the explosion is another strategy by the agency and Fukuchi not being able to retrieve the One Order, he rushes outside completely halting his search.

After hearing the explosion, Fukuchi contacts Teruko and Tetchō but receives no response. Suddenly, the plane carrying One Order swiftly descends. Teruko and Tetchō arrive just on time with the latter activating his ability, resulting for the plane to be completely teared down. As the plane descends, Fukuchi catches the One Order and successfully obtains it. He then regroups with Teruko and Tetchō. With One Order in his hands, Fukuchi tries to open it but failed to do so, realizing that the box containing it is sealed by an ability and wonders who might be responsible for it.

Unable to use the One Order, Fukuchi rushes to Bram's location with the plan to initiate a war. Fukuchi plans on having on the  and landing rocket artillery destroyers and  on airborne worldwide divisions, together with launching his vampire army by using the Holy Sword attached to Bram's body as a trigger. Upon reaching the room where Bram is, he calls out to him but finds the coffin empty.

After finding out that Bram is not present at his coffin and being unable to initiate the vampire infection without Bram, Fukuchi gathers all the vampires and orders them to blockade the airport, find Bram, and kill the culprit, whom he thinks is an ally of Jōno. With Fukuchi sending out his orders to the vampires to look for Bram, he is later told by Teruko that Tetchō has lost against an Agency detective, compelling him to join the manhunt for Bram.

Fukuchi uses Amenogozen in the future to send out signals to his past self, hence his current self, which blocks in the airport is Bram not found, filtering them out one by one with a corresponding map of 256 boxes covering a large portion of the airport to search. Upon eventually finding out that he is a certain block H5, Fukuchi later resurfaces behind Kunikida—who is looking for his fellow detective who suddenly turns up missing—and prepares to strike with his blade.