Driven out from his orphanage, Nakajima Atsushi wanders the streets of Yokohama on the bring of starvation. Determined to live, a chance encounter with a drowning stranger changes his fate...

Despite joining the Armed Detective Agency, Nakajima lacks conviction that he'd be of any use. Just as he's about to bid the agency farewell, a bomber takes over the agency with one of the agency employees as his hostage...!

Now an official member of the Agency after passing their entrance exam, Atsushi is assigned to his first case right away with Tanizaki and Naomi. Though deceptively simple on the surface, there's more than meets the eye...

Though saved from the Port Mafia by Dazai's intervention, Atsushi feels responsible for bringing trouble to the Agency's door. Rather than risk another attack because of him, Atsushi decides to leave the Agency and makes a call to the Port Mafia...

After repelling the Port Mafia's Black Lizards with deceptive ease, Atsushi is tasked with accompanying Rampo to a case. Skeptical of the self-dubbed great detective who seems to lack all common sense, Atsushi is about to witness Rampo's ability first-hand...

The Agency investigates a series of disappearances in Yokohama. Kunikida enlists the help of a hacker named Taguchi Rokuzou, but all they find are photos of the victims and mention of a mysterious figure called the Azure Messenger. They follow the trail of clues to an abandoned hospital...

Following the Azure Messenger's bomb threat, the Armed Detective Agency must race to prevent the deaths of hundreds, which would taint the Agency forever. However, Dazai's seemingly distracted by Sasaki Nobuko, the lone survivor of their raid on the abandoned hospital...

Dazai goes missing, but the Agency operatives feel it's just business as usual. Meanwhile, Atsushi accompanies Yosano Akiko on a shopping expedition, where they are suddenly plunged into the middle of a terrorist bomb threat by one of the Port Mafia...

Kyouka was made into an assassin by those who abused her ability, and Atsushi can't help but feel sympathy toward her. Unable to turn her in to the military police, Atsushi ends up taking her out on a date. Meanwhile, Akutagawa is busy berating his former supervisor--Dazai.

Dazai has a face-off with his ex-partner, Chuuya, as Chuuya attempts to uncover Dazai's true intentions for letting himself get captured. Meanwhile, Atsuhi faces Akutagawa's intense and inexplicable hatred for him, as the ship continues on to the meeting place where he will be handed off in exchange for the bounty on his head...

In the aftermath of Atsushi and Dazai's abduction, the Agency must decide what to do with Kyouka, the loose end. Meanwhile, the Port Mafia also deliberates what to do with Akutagawa, now comatose, as his enemies seek vengeance...

Francis, the leader of The Guild, a North American organization of gifted members, is the one responsible for the bounty on Atsushi's head. Fukuzawa refuses Francis's offer to buy out the Agency, but their agents begin to disappear...

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.