Due to the many characters of differing ages and the supplemental novels taking place at different times, organizing this timeline is one of the most troublesome, time-consuming, headache-inducing tasks one can undertake. Obvious spoilers for the entirity of the series below. Secondary bullet points mean that they are a set of events that happened under the nomer in the singulary bullet point above, or if they all happened the same year (this is particularly the case with births). Italics indicate the source of this happenstance if it is outside of the main manga. This timeline follows the manga, not the anime for various reasons.
- Hirotsu Ryuurou is born on July 15
- During the same year, Santouka Taneda is born on December 3.
- Five years later, Yukichi Fukuzawa is born on January 10.
- Presumably around the same time or after Ryuurou's birth, Ouchi Fukuchi is born, presumably on May 13. note
- Four years later, Ougai Mori is born on February 17.
- Nine years later, Francis Scott Key Fitzgerald is born on September 24.
- Four years later, Edgar Allan Poe is born on January 19.
- 29 days later, Motojirou Kajii is born on February 17.
- A year later, Nathaniel Hawthorne is born on July 4.
- Two months and twenty-two days later, Sakunosuke Oda is born on October 26.
- A year later, Kouyou Ozaki is born on January 10.
- Two months and twenty-two days later, Nikolai Gogol is born on April 1.
- Six months and twenty days later, Ranpo Edogawa is born on October 21.
- A year later, Akiko Yosano is born on December 7.
- Two years later, Katai Tayama is born on January 22.
- A year later, the original Chuuya Nakahara is born on April 29.
- One month and twenty-eight days later, Osamu Dazai is born on June 19.
- Two months and eleven days later, Doppo Kunikida is born on August 30.
- One month and twenty days later, Ango Sakaguchi is born on October 20.
- One month and ten days later, Mark Twain is born on November 30.
- A year later, John Steinbeck is born on February 27.
- A year later, Ryuunosuke Akutagawa is born on March 1.
- Eight months and a week later, Margaret Mitchell is born on November 8.
- A year later, Michizou Tachihara is born on July 30.
- Four months later, Lucy Maud Montgomery is born on November 30. She grows up in an orphanage where she is harshly treated.
- A year later, Atsushi Nakajima is born on May 5. This boy too grows up in an orphanage where he is harshly treated.
- Somewhere between this point and the Dragon's Head Conflict, Atsushi kills the first incarnation of Shibusawa when electrical torture goes wrong. (DEAD APPLE)
- Two months and nine days later, Junichirou Tanizaki is born on July 24.
- Four months and nine days later, Louisa May Alcott is born on November 29.
- A year later, a photo of Chuuya Nakahara is taken, he is 5 at the time. At some point within the next 3 years, he is abducted and experimented on by the government. In the process, a clone Chuuya is created and modified to house Arahabaki.
- Three years later, Kenji Miyazawa is born on August 27.
- Two months, a week and one day later, Kyouka Izumi is born on November 4.
- In the same year (the original Chuuya is 7 by then), Rimbaud and Verlaine attempt to steal Arahabaki. This goes awry and wipes Rimbaud's memories (FIFTEEN). One of the Chuuyas merges with Arahabaki and is released, though whether he is the original or the clone is unknown.
- Tachihara's brother performs suicide after having given Yosano her butterfly hairpin. Yosano is aged 11 by then (and Mori is 32).
- Odasaku is an assassin. He meets Fukuzawa and Ranpo. (Dark Era)
- Kouyou attempts to run away from the mafia. (For reference: Dazai is 10 by then)
- A year later, Kyuusaku Yumeno is born on January 4.
- Ougai Mori becomes an underground doctor after the Great War. He is a surgeon on neutral territory amidst of a gang war.
- Fukuzawa, an assassin aged 32, meets Ougai Mori. They clash often, but when they work together, they are invincible.
- Odasaku meets Souseki and stops killing. (Dark Era)
- Some time later, he joins the mafia and becomes their handyman. (Dark Era)
- Fukuzawa meets Ranpo and founds the Armed Detective Agency with the help of Souseki to protect the boy. (Founding)
- Yosano joins the Armed Detective Agency, defecting from her work at the ship.
- Kunikida joins and Katai joins too, to leave it some time later. (Founding)
- Mori retires from his work as an underground doctor and murders the boss of the Port Mafia because the Mafia would've gone to its demise if he lived. Dazai, who cannot be older than 14 at that point, watches in silence.
- Fukuzawa and Mori are put together in a great scheme of things by Natsume Souseki, called The Tripartite Tactic together with the Government.
- Ango goes undercover in the Mafia. (Dark Era)
- FIFTEEN/The Blue Era
- Dazai turns 15.
- Rimbaud dies.
- Chuuya defects from the Sheep and joins the Mafia.
- He receives Rimbaud's hat.
- Storm Bringer
- Chuuya, age 16, and his friends celebrate Chuuya's first year in the mafia. Soon after, they are murdered by Verlaine and Chuuya joins forces with Adam Frankenstein to get revenge.
- The Chuuya left in the lab perishes.
- Chuuya learns of his past as a government experiment and with the help of Dazai, also age 16, uses Corruption for the first time to defeat Verlaine.
- Verlaine is locked up by the Port Mafia. At some point six years later, he becomes an executive.
- The Day I Picked Up Dazai
- Dazai meets Oda and recruits him into the Port Mafia sometime after Verlaine is dealt with, but before the Dragon's Head Conflict.
- Dragon's Head Conflict.
- Oda takes the orphans in (starting with Sakura, DEAD APPLE).
- Ango goes abroad to Europe, presumably to meet a car broker. (Dark Era)
- Mimic is first heard of. (Dark Era)
- Mori declares Dazai as the best candidate for executive.
- Chuuya kills Shibusawa's second incarnation as a reaction to Shibusawa killing his friends. (DEAD APPLE)
- Dazai becomes executive.
- The very same day, Akutagawa is recruited by him.
- The Dark Era. note
- Dazai turns 18.
- Mimic enters Yokohama.
- Ango is revealed as a triple spy and returns to his position in the Government.
- Oda dies at age 23.
- The Mafia obtains the Permit.
- Mimic is wiped out.
- Dazai leaves the mafia.
- Somewhere between Q's birth and this point, Dazai locks him up. This is the last point in the timeline when this could have happened.
- Dazai spends his time anonymously, while Ango cleanses his records.
- Dazai is 19 and Atsushi is 15 as Sigma is created by the Book.
- Kyouka's parents are killed.
- Kyouka joins the mafia under Kouyou's tutelage.
- Azure Messenger runs amok. By the resolving of this, Dazai passes his Entrance Exam for the Agency. The Gaiden events cannot happen earlier than this moment.
- The Tanizaki siblings join the Agency.
- Kenji joins the Agency.
- Somewhere after the Dark Era but before the main series, Higuchi joins the mafia. This is the last point in the timeline where this could have occurred.
- Chuuya becomes an executive sometime after Higuchi joins.
- Two months later, Atsushi is kicked out of the orphanage. note
- He joins the Agency.
- The Mafia and the Agency fight.
- Atsushi saves Kyouka.
- Guild Arc
- The Guild enters Yokohama.
- Atsushi and Tanizaki defeat Lucy.
- Nathaniel Hawthorne and Akutagawa fight, resulting in a victory for the latter. Margaret Mitchell ends up in the hospital.
- Q is released out of prison and kidnapped by Steinbeck, sending the city into chaos.
- Atsushi and Dazai save the day.
- Double Black is sent to retrieve Q. They fight against Lovecraft.
- Akutagawa and Atsushi defeat Fitzgerald in a united battle.
- Kyouka passes the Entrance Exam as well.
- The Guild splinters.
- Nathaniel Hawthorne approaches Fyodor and is brainwashed by him.
- Bungo Stray Dogs: Dead Apple
- Shibusawa's third incarnation arrives at Yokohama, working together with Dazai and Fyodor.
- The mist spreads in Yokohama, splitting Abilities from their owners.
- Akutagawa, Kyouka and Atsushi meet up and fight against their Abilities. The three eventually win.
- Shibusawa and Dazai are killed by Fyodor, who revives the former into Singularity.
- The true form of Draconia Room appears as a giant dragon, which Chuuya defeats.
- Chuuya finds Dazai in the chaos and wakens him.
- Atsushi gets his Ability back and defeats Singularity.
- Everything is back to normal.
- Lucy finds a new job at Uzumaki.
- It is revealed that Gin is a sister of Akutagawa.
- The Headmaster dies.
- Kyouka's past is revealed.
- Cannibalism Arc
- Ace is killed by Fyodor.
- Fyodor pits Mori and Fukuzawa against eachother with Pushkin's Ability. He uses the brainwashed Hawthorne to carry out his plans.
- Fitzgerald builds up the Renewed Guild in another country, with Alcott at his side. They obtain the 'Eyes of God'.
- Steinbeck founds the Remnants of the Guild.
- Souseki comes in to save the day and give Fukuzawa and Mori courage after a lengthy duel.
- It is revealed that the Special Abilities Government Division leader Santouka Taneda is in the hospital.
- Akutagawa and Atsushi defeat Ivan Goncharov.
- Pushkin removes the virus.
- Ranpo meets Mushitarou Oguri.
- Sunday Tragedy
- The Decay of the Angel lead the Agency into a trap and rewrite the book to frame the Agency. From this moment, the Agency is scattered.
- Nikolai Gogol is presumed dead.
- Hound Dogs
- The Hunting Dogs are called in to find the scattered Agency members.
- Tachihara reveals his true nature and his Ability.
- Mushitarou Oguri breaks out of jail, with some help of Atsushi and Kyouka.
- Kunikida, Fukuzawa and Dazai are captured.
- Dazai meets Fyodor in prison.
- Ango decides to help Oguri, Atsushi and Kyouka. The effect of his Ability is revealed.
- Atsushi, Kyouka and Lucy go to the sky casino of Manager Sigma, a member of the Decay of the Angel. Tachihara and Teruko soon follow.
- The Hunting Dogs face Sigma. Part of Sigma's past is revealed.
- Ranpo saves Kunikida (whose hands were cut off earlier) and Yosano. He teams up with Poe, who safeguards Katai by using his Ability.
- The aforementioned Ranpo is struck by an "Eureka!" Moment, and figures out that Fukuchi is Kamui.
- Fukuchi uses Bram Stoker to make Akutagawa into a vampire. He proceeds to infect the rest of the Black Lizard squad.
- Tachihara defects to the Port Mafia and faces Fukuchi in battle. He is blinded.
- The vampire infections spreads to numerous other countries at a rate that will allow Fukuchi to control half the world's military in four days.
- Ranpo gathers the Agency in a seperate room created via Poe's Ability and explains that Fukuchi is aiming for a device that can control anyone indefinately. Tanizaki and Kenji appear soon after gathering, having met Mori in the time that was spent, who told them to gather. Within 20 hours, Fukuchi will retrieve the artifact.
- Fukuchi proposes that Jouno becomes a member of the Decay of the Angel. He has noticed that, to end all chaos, Bram can just be killed as a means of Cutting the Knot. This is why he asks Jouno to prevent that from happening. Jouno agrees, but then attacks Fukuchi.
- Jouno's Ability is revealed, but despite his attempts to escape is stabbed numerous times and bitten by Akutagawa. Aya takes a photo of Fukuchi and is hunted down by him.
- The ADA decide to use their status as terrorists to halt the hand off of the One Order by making the British government believe the delivery is unsafe. When Fukuchi retrieves the artefact, he finds it sealed by a yet unknown Ability.
- Fukuchi fails to find Aya, who hides in Bram's coffin to the vampire's anger. After a short conversation, Aya flees with Bram in tow.
- Nikolai frees Dazai and Fyodor out of prison.
- When given the choice of a tool for escaping the prison, Fyodor chooses a key card and Dazai chooses Sigma.
- A vampiric Chuuya arrives in Meursault and massacres the guards to aid Fyodor.
- Bram aids Aya in evading the vampires and she is rescued by Kenji.
- Kenji battles Tecchou.
- Atsushi plays a video Tachihara made, revealing the truth about the ADA, to Teruko and she agrees to help them on the condition that she meets with Ranpo.
