atsushi father was mori, biologically but mori was never there for his son. He was always too busy with work, atsushi was spoiled, mori has money so he just gave atsushi money and left it at that, atsushi was took care by maid. Atsushi never had his father, atsushi was just alone, his mom wasn't in the picture.

the agency knows nothing about atsushi father being mori, the agency was enemies with the port mafia.

(You chose what happened, kill mori off or something)