The show is pretty childish in how it shows violence and moral dilemmas, but right now it seems to have some darkness and DEEP under the skin. Perhaps that will come out soon, but personally, I wouldn´t count on it.
The plot is that in Japan, the government creates a censorship commitee that slams down hard on all the media. The better protected one is literature, with books and magazines defended by a paramilitary organization formed by specially trained squads operating from, and in libraries (there are legal restrictions on how the fighting can be carried out).
Basically, it´s like two police forces opposed to each other, fighting each other with the law in one hand, and a gun in the other. Many seem to think this is a civil war, and therefore retarded because Japan is still supposed to be pretty peaceful despite a shoot-out now and then. That´s because this isn´t a civil war (although it seems to be heading that way), but rather... police actions, so to speak.>I think it's cute how they get so worked up over books too.
The presentation is childish, but it hides some DEEP under that.