(Bit of a update!) odasaku use to also take of atsushi, every kid that odasaku took care of, never had any connections with the port Mafia but atsushi has a ability so mori wants him.

odasaku didn't die but leave after all the kid die, he couldn't take atsushi so he has to leave atsushi behind, which he didn't want to do. Dazai also left with odasaku.

many years later, both dazai and odasaku work at the agency, today fukuzawa was in the main office, waiting for someone, he was waiting for atsushi

Yosano(whispering): who do you think the president is waiting for?"

yosano whispers to ranpo, ranpo already knew, he know everything.