I think the manga you're referring to is On Doorstep by CTK/Chongtak. This is the summary:
Jimmy, a small-time thief, is caught pickpocketing by a middle-aged guy named Reese. Instead of handing him over to the police, Reese makes him slog hard for a day at the book store where he works. Wanting to get back at the other man for humiliating him, Ji......
Ryousuke's hair is so fucking stupid. I cannot take him seriously in this chapter. Why is his hair so long on one side? It shouldn't bother me so much, but it's so dumb. It's so dumb. I've lost the ability to word because of his hair.
Given the overall theme of this manga, the ending should not have come as a surprise... yet I am DEVASTED. I was not expecting that AT ALL. I need some emotional support right now. *ugly sobbing*