Dark Era Arc

Dark Era Arc (の,) is chronologically the fourth background arc of Bungo Stray Dogs. It tells the story of Dazai when he is still part of the Port Mafia.

Synopsis
Before joining the Armed Detective Agency, Osamu Dazai was the youngest executive with the Port Mafia, the most notorious underground crime syndicate in all of Yokohama. When one of their colleagues suddenly goes missing, Dazai and fellow Port Mafia members, Sakunosuke Oda are tasked with conducting an investigation.

Ango's Disappearance
Mori summons Oda in his office with an uknown agenda. After Oda arrives, Mori tells him about what will his mission be - to find Ango Sakaguchi, the intelligence officer of the Port Mafia. Mori briefs Oda about the situation wherein Ango disappeared last night, the cause of his disappearance whether he was kidnapped or run away at his free will, was unknown. Shorly after the briefing, Mori pulls out a paper and writes on it. Mori tells Oda that the document also known as the Silver Oracle will aid Oda if he need any assistance on his investigation whether ordering executives or other memberes of the Port Mafia. Mori soon hands out the document and Oda accepts it before leaving the place.

Appearances
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Chapters

 * Prologue
 * Chapter 1
 * Chapter 2
 * Chapter 3
 * Chapter 4
 * Epilogue

Impact

 * Dazai left the Port Mafia.