Oh, a detective! So that means all of this investigation stuff is pretty familiar to you, isn't it?

[ that's certainly a useful skill, given their situation; dazai makes a mental note of it. but he also opts not to ask for elaboration on that lengthy case — because solving cases is a detective's pride... or something of the sort, and he doesn't want to make him uncomfortable. ]

Maybe... you were working so hard on that case that you subconsciously wanted to rest? [ it's out there, and not too good of a guess, but he's trying. ]

Honestly, I'm surprised you even remembered what you were doing before you came here. As for me, I can't recall anything.