PRESENT EVENTS
— everything that came after the start of the manga.
The Armed Detective Agency vs. The Port Mafia Arc
Atsushi meets Dazai and Kunikida, who was in search of a tiger roaming around, which turned out to be Atsushi.Dazai recruits Atsushi to the Agency, who passes the Entrance Exam and is taken under Dazai's care.Akutagawa attempts to capture Atsushi because of the bounty on his head, but Dazai stops him before he could.Atsushi is assigned to be on a case with Ranpo, where his ability is revealed to be fake.Dazai gets captured by the mafia, but is released afterwards.Kyouka defects from the mafia.Akutagawa fights Atsushi and Kyouka, and ends up in a coma.Higuchi and the Black Lizard saves Akutagawa.
The Guild Arc
The Guild arrives in Yokohama, in search of the book.Fitzgerald asks Fukuzawa for the Special Ability Permit, who refused.The Guild members attack both the Port Mafia and the Agency, resulting in a three-way war.Atsushi is captured by the Guild.Kyouka is arrested by the police and is put in a plane.Fitzgerald planned to destroy Yokohama with Moby Dick and leave Atsushi alive, as he is 'the guide to the book.'Margaret ends up in a coma after a fight with Akutagawa.Atsushi and Akutagawa fights off Fitzgerald, and ends up winning.Atsushi manages to stop Moby Dick from crashing, but the system was hacked by Fyodor, who attempts to make it crash again.Kyouka crashes the plane she was in, against Moby Dick.Kyouka passes her entrance exam and is declared the newest member of the Agency.The Guild is dissolved.
The Guild Aftermath
Fyodor is captured by Ace.Ace kills himself.Fyodor kills Karma and Ace's other men.Lucy starts working at Café Uzumaki as a maid.Kyouka discovers the truth about her parents' death.the orphanage director is hit by a truck and dies.it is revealed that Gin is Akutagawa's sister.Hawthorne gets brainwashed by Fyodor.Steinbeck becomes the leader of the remnants of the Guild as Fitzgerald is presumed dead.
55 Minutes*
the Agency gets sent on a mission to Standard Island.**
*the fourth light novel of BSD.
**I don't want to say any more than that since it'd be better if you read it for yourself.
DEAD APPLE*
Shibusawa returns, and worked with Fyodor and Dazai.
*a separate manga and movie, but is in the canon timeline.
I recommend you to watch/read it because the events are very confusing to explain.
Cannibalism Arc
Fyodor pits the mafia and the agency against eachother, using Pushkin's ability to create a virus. Fyodor uses Hawthorne for his plans.Fitzgerald builds up the Guild with Alcott. They obtain the 'Eyes of God'.the Agency and the Port Mafia fights, while their respective leaders are bed-ridden.Fukuzawa and Mori leaves to meet up in a place only they know, in order to settle who wins.Natsume breaks up the fight against them and tells them to ally instead.Akutagawa and Atsushi are sent to Fyodor's presumed base.Shin Soukoku defeats Ivan Goncharov, one of Fyodor's men.Pushkin removes the virus from the affected victims.Dazai attempts to capture Fyodor and succeeds, and Fyodor is sent to Mersault.
Decay of Angels Arc
Ranpo goes on a case, one which stumps him for awhile.Ranpo meets Mushitarou Oguri, deeming him the criminal.Oguri warns him of what's about to come.the Agency is framed by the Decay of Angels, the public now knows them as terrorists.Nikolai Gogol is presumed dead.
the Hunting Dogs are sent to capture the Agency.Atsushi and Kyouka breaks Oguri out of jail.Kunikida, Fukuzawa and Dazai are captured.
Dazai is sent to Mersault, where Fyodor currently is.Ango helps Atsushi, Oguri and Kyouka escape from the Government.Oguri currently resides in Poe's mansion.Atsushi, Kyouka and Lucy goes to the Sky Casino, with Ango as their current leader.Sigma, the manager of the Sky Casino, is introduced.Tachihara and Teruko also arrives at the Sky Casino and faces off against Sigma.around this time, it's revealed that the Casino and Sigma are from the book.
Ranpo saves Fukuzawa, Kunikida, Yosano and Katai, with the help of Poe.the whereabouts of Tanizaki and Kenji are currently unknown.Ranpo goes to meet Fukuchi to ask him to be an ally.until Ranpo realizes that Fukuchi is 'Kamui,' and pushes Atsushi out of harm's way and puts himself in one of Poe's books.
Atsushi faces off Fukuchi alone, until Akutagawa shows up.Shin Soukoku attempts to defeat Fukuchi, but ultimately fails.Akutagawa is struck by Fukuchi's sword.
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To be continued.
Manga scans are from @dazaiscans on tumblr, and the light novel scans are from @akutagawaprize on tumblr. Please consider checking them out!
References for the timeline itself is from the BSD Fandom Wiki, the tvtropes.org's BSD timeline, and of course, the manga and light novels.