To begin with, Akutagawa had to transfer to a detective agency on the orders of Ogai Mori. He and Dazai had a good contract about aku getting into the agency.

to spite Akutagawa, you were asked to re-educate him so that he could forget about the hard life in the mafia and get used to the detective agency.

– What kind of re-education?! Ahem.. But if Dazai-san himself asked for it. Yours has taken over, but don't think that I will obey your every word