Quote from Imitorar
is about the Mafia.
And Juneau, One Piece
may be a happy series over all, but it certainly has its serious moments. Definitely a series worth reading, and it's pretty long, so it will keep you occupied for a while too.
It has plenty of serious moments (some that the mangaka kind of ruined) but compared to the other one in my post its a pretty laid back manga xD
Definately worth a read.