Death is the end... but not quite. The dead can send one last message to the living. This is usually a handwritten letter, but it can also be a parcel. Anything that can be carried by the Shigofumi delivery girls, basically.
This series is about that. By definition, someone either dies or is dead already in every episode. The show's not as dark as you'd think and even has its own charm, but sometimes it's shocking. What we see in the bullying episode (ep.6) is so vile that the slightly goofy payback in ep.13 doesn't work. We want these people dead. Some of what happened was hard to watch. Schoolboys and schoolgirls commit suicide, which might later be dismissed by others as "childish". Children shoot their parents, who in turn abuse or kill their children. (One of those letters is from a foetus to the man who arranged its abortion, delivered as he gets beaten up by other pimps for getting another prostitute pregnant. The letter's just a bloody handprint.)
The show has a fairly sour view of society. The police can jump to insulting conclusions. We meet some dreadful parents. A school where students commit suicide is only concerned with avoiding embarrassment. "Don't say anything unnecessary to the press."
Despite all that, though, the show's basically quite nice. The protagonist (Fumika) delivers shigofumi, which is a job that's normally reserved for the dead. Nonetheless, two of her old classmates recognise her and start investigating. We meet another shigofumi (Chiaki) and some chatty magical staves. Ep.9 could be summarised as "the gang go on holiday together", although of course there's going to be a lot underneath that.
It also helps that shigofumi carriers can handle themselves. They're young girls who often walk into dangerous situations, but I can't remember a time when anyone beat one in a fight. They can turn invisible, sprout angel wings and hit people with that magical staff (although the staff might complain about it afterwards).
This is capable of being a strong show, showing us teen suicide, child abuse/exploitation, mental illness, pressure for social conformity and one of the nastiest anime portrayals I've seen of bullying. At the same time, though, its main cast is likeable and the show ends up exploring the issues and history of Fumika herself. The show's not as traumatic as you'd think. Despite some horrors, I enjoyed it.