This story arc or saga name is not official. This story arc or saga has no official name and is subject to change at any time.
Azure Apostle Arc (蒼の使徒編,,Ao no Shito-hen?) is chronologicly the fifth background arc of Bungo Stray Dogs. It tells the entrance exam of Dazai in order to join the Armed Detective Agency with the help of Doppo Kunikida.
Doppo Kunikida is an idealist and a straitlaced detective at the Armed Detective Agency, he's paired up with the agency's newest hire: a suspicious, eccentric, suicide-obsessed man named Osamu Dazai. Their first case together turns out to be far more complicated than Kunikida anticipated -- and it looks like the detective agency's sworn enemy, the Port Mafia, is somehow involved, too!