中島敦撞見太宰治再度意圖自殺後，終於受不了了。太宰介紹他加入武裝偵探社。

敦與太宰一同前往偵探社辦公室，但非常缺乏自信的他卻考慮退社，直到發生了一場緊急事件。

敦與谷崎潤一郎和他的妹妹奈緒美聯手，承辦第一件案子。這項在橫濱進行的任務頗為簡單，但當地卻是港區黑幫的地盤。

被芥川和樋口弄得元氣大傷的敦，把橫濱發生的事情怪到自己頭上。與此同時，廣津柳浪與黑蜥蜴採取行動。

敦雖然懷疑江戶川亂步的能耐，卻依然陪著自封全日本第一名探的他，一起調查一樁兇殺案。

國木田與太宰調查橫濱的一連串失蹤案。駭客田口深信他們都跟神出鬼沒的「蒼之使徒」有所牽連。

偵探社奮力調查蒼之使徒的炸彈威脅。太宰偵訊醫院襲擊事件唯一的生還者佐佐城。

敦雖然很擔心太宰，依然陪晶子去購物，但這趟外出之旅卻因為港區黑幫攻擊他們的火車而濺血。

敦和國木田力圖釐清鏡花的能耐，以及她過去跟港區黑幫有何牽扯。國木田想把她交出去，敦卻下不了手。

太宰的老搭檔中原中也正面槓上他，要求知道太宰當時讓自己被抓的原因。另一方面，敦再度和芥川面對面。

鏡花請求福澤諭吉讓她加入偵探社。芥川陷入昏迷後，樋口得拼命鞏固自己在港口黑幫的地位。

法蘭西斯·史考特·費茲傑羅和組合終於透露自己的身分，並提議收購偵探社，雖然被福澤回絕，費茲傑羅卻不願罷休。

On a misty night, Oda Sakunosuke, Dazai Osamu, and Sakaguchi Ango meet as always at their usual bar. For the trio of Port Mafia members, it a night spent in camaraderie like any other, but Ango vanishes that very night. Oda is given a direct order from the Port Mafia boss to find Ango, but...

The reason that Odasaku went to a certain Western style restaurant was not just because of the curry. He is having the owner watch over a group of young children who had lost their parents two years ago in the war. Odasaku is trying to track down Ango, and remembers the time they first met. Meanwhile, Dazai manages to catch one of the Mimic soldiers alive in a trap he had set. However, once he gets there, all that is waiting for him is a corpse. Another figure was also waiting for him, his subordinate, Akutagawa Ryuunosuke.

The Port Mafia's council of five top executives has decreed that Mimic must be annihilated. In the ensuing battle, Odasaku has a fateful encounter with Gide, the leader of Mimic, who makes a cryptic prophecy. Night falls, and the usual bar now awaits Dazai, Odasaku and Ango...

While the leaders of the Port Mafia and the gifted special operations division meet via Ango, Dazai is close to discovering the true significance of the conflict between the three groups. However, in despair, Odasaku's deaf to Dazai's entreaties not to go alone to Mimic's headquarters where Gide awaits...

Trusting in a life that doesn't require her to kill, Kyouka works her first job at the Armed Detective Agency, but the job ends in a minor disaster. As Atsushi attempts to cheer her up, the unthinkable happens--Kyouka's inactive cell phone rings, and a voice orders Demon Snow to attack Atsushi.

Mori, the leader of the Port Mafia, sends a letter to Margaret M. and Nathaniel H., threatening to destroy them and the ship they are protecting.

John S. and Lovecraft hunt down Naomi and Haruno as they flee from town. While Atsushi and Dazai wait for them to arrive at the train station, Dazai notices a shady figure stalking him.

Atsushi is abducted onto the Moby Dick. Meanwhile, Lovecraft succeeds in capturing Q. Francis F. and the Guild prepare to carry out what they call their "emergency plan."

The leaders of the Agency and the Port Mafia negotiate an alliance. Meanwhile, Dazai and Chuuya face off against Lovecraft.

Rampo receives an invitation to a detective game from none other than E. A. Poe. He's indifferent at first, until Poe reveals what the reward would be should he win.

Atsushi searches desperately for the control terminal, which he would need to stop the Moby Dick from crashing into Yokohama. He's greeted by Akutagawa and Francis, both of whom have other plans in mind.

Atsushi and Akutagawa fail to call off the Moby Dick's descent. They search desperately for other ways to protect Yokohama.

Port Mafia leader Mori Ougai orders a fifteen-year-old Dazai Osamu to investigate the appearance of a certain individual in the Yokohama Settlement area.

Dazai Osamu and Nakahara Chuuya are attacked by GSS soldiers in the middle of investigating an explosion caused years ago by Arahabaki.

Nakahara Chuuya and Dazai Osamu reveal the truth behind Arahabaki, Randou, the former Port Mafia boss and Chuuya himself.

Port Mafia executive Ace captures Fyodor, who was behind the destruction of the Moby Dick. Keeping him captured may prove to be more difficult.

The Agency is tasked with finding and delivering an important document. A man is hit and killed by a truck. His identity shocks Atsushi.

Louisa reunites with Fitzgerald, but he’s not quite the man he used to be.

The leaders of the Port Mafia and the Detective Agency are attacked by an assassin in a mask, leaving both of them ill.

Tensions between the Detective Agency and the Port Mafia run high as they both scramble to save their own leaders while avoiding an all-out war.

The Detective Agency president is in safe hands for now, but unless he or the Port Mafia boss dies, a full-scale war between the two organizations is inevitable.

Mori Ougai and Fukuzawa Yukichi fight to the death in a desperate bid to save the organizations they lead from falling into a devastating war.

The gifted responsible for the virus is on the run as Nakagawa Atsushi and Akutagawa Ryunosuke chase after him. Meanwhile, the Detective Agency has the Rats’ hideout surrounded to try to capture Fyodor Dostoevsky.

Security police officer Fukuzawa Yukichi arrives at work to discover that his client had been assassinated. The assassin is already apprehended by the time he arrives, but something doesn’t quite seem right.

Fukuzawa gives Rampo a pair of glasses, claiming that wearing them would activate his ability to instantly determine the truth of any situation, and taking them off would give him the ability to tolerate the stupidity of the ordinary person.

Rampo gets a ride to the police station, but the officer doesn’t seem to be who he says he is.

Kunikida is being held for a murder that Rampo is certain he didn't commit. Meanwhile, Poe is determined to solve a murder mystery that has had the police stumped. Rampo has some thoughts on that situation, too.

The last page of the manuscript received by Poe appears to have been a photocopy. Rampo seems to know why, but there are still more mysteries surrounding the death of the author.

The Detective Agency receives an urgent request from the government to investigate a series murders perpetrated by the same culprit.

The Detective Agency is framed for the brutal murder of several government officials. Its members are on the run from the Military Police.

The president of the Detective Agency is arrested, and Kunikida is missing after having blown himself up with a grenade. Meanwhile, Atsushi and Kyouka are on the run, looking for a way to defeat the true mastermind: Fyodor.

Port Mafia boss Mori wants Yosano to join them in exchange for assisting the Detective Agency through their crisis. Yosano reveals why she would rather not.

Tanizaki, Miyazawa and Yosano head to the site where Yosano is scheduled to be handed off to the Port Mafia.

Atsushi and Kyoka help Mushitaro escape. However, they get surrounded by the Bureau, led by Ango Sakaguchi.

Suspecting that Lucy is cooperating with the terrorist organization known as the Armed Detective Agency, Jouno and Tetchou pay a visit to the cafe at where she works, in hopes of tracking down Atsushi and Kyouka.

Teruko goes head-to-head with Sigma. Tachihara rethinks the Agency’s innocence after re-infiltrating the Port Mafia.

The members of the Agency, isolated and unable to communicate with each other, are victims one after the other of assassination attempts, thwarted in extremis by a mysterious guardian angel. Who is this ?

As Fukuchi allies with plans to create an international anti-terrorist organization targeting Gifted, Atsushi and Rampo appeal to him for help. Rampo turns his immense detective abilities to the question of Kamui's identity, and the truth will change everything.

Atsushi and Akutagawa find themselves cornered, with no choice but to fight Fukuchi and his seemingly insurmountable powers. Combining forces and trusting in one another, do they have what it takes to defeat the mightiest Hunting Dog?

The last member of Decay of the Angel is revealed. Kamui continues to spread chaos. Tachihara entrusts Fukuchi with the information device containing evidence obtained at the Sky Casino, only to face devastating consequences.

The Detective Agency races to stop Fukuchi from receiving the One Order, a devastating mind control weapon that will make his plans for world domination unstoppable.

Fukuchi's plans and the Agency's attempts to thwart him escalate, and Aya comes face to face with Count Bram. Meanwhile, Nikolai and Sigma move to rescue Dazai and Fyodor from prison, but Nikolai has more than rescue on his mind...

As Atsushi races to find Teruko, Kenji arrives to help Aya and Bram escape the airport.

Kenji fights to help Atsushi, demonstrating why he is one of the most dangerous Agency members. Meanwhile, Dazai's machinations within the prison become clearer.

Fukuzawa and Fukuchi confront their shared past as time runs out for the Detective Agency.

Dazai and Sigma are trapped in a flooding room. Atsushi is attacked by Akutagawa when he attempts to help Aya. During their fight Aya desperately tries to remove the holy sword from Bram.

The final pieces of Fukuchi's plot snap into place, trapping Fukuzawa in a way not even Rampo could anticipate. At the same time, Fyodor and Dazai's deadly game draws to a close.