End photography

It's ryoji. This is an artistic rendering technique, which sets off the inner contradictions and helplessness of the protagonist. The jobs that good governance has never been warmed by society include the lowest jobs: killers, male prostitutes and manual workers (the image described in your question). Crying is the pouring of contradictions in his heart.

I think from a literary point of view, Nocturnal Walking and The Great Gatsby are of the same kind. If you are interested, you can read it, and you will have a deeper understanding of Keigo Higashino's Night Walk.