There's something that gets slightly lost in translation that really helps explain Seiichirou, and this bit in the novel does a really good job at touching on it
The word that often gets translated as "working adult" is 社会人 (shakaijin). The literal translation is 'person of society.'
Now, obviously, it can be easy to forget the base of words in your native language, so I'm not gonna pretend that explains everything about the man lol
But this part of the novel does imply it's not too small a piece. And I just think that's neat.
