For a few months out this anime, it was useful enough, I must confess that I finished watching the recommendation of 2 friends appearance as I left the impression of "typical anime high school and teenage problems, but this anime is very far from it.
The story follows the main protagonist Otonashi, a teenager who lost his memories of his life after death. To awaken the afterlife, he meets a girl named Yuri who invited him to join the Shinda Sekai Sensen (SSS), an organization she founded and runs counter to God, by the cruel fate that befell his brothers in life, the SSS members with experience in life have as their only enemy in the school council president, Angel, a being with supernatural powers that are responsible for maintaining the status quo and the struggle against the SSS. Anyone who follows the orders of angels and behaves like a normal student in school will eventually disappear "and go to heaven", although people do something they could do in life also disappear.
In the SSS, there are two sub-divisions that assist in the operations of the SSS against the Angel. The first is a band of four girls called Girls Dead Monster, whose goal in the SSS is to cause a distraction for other activities that SSS performs. This includes distract Angel and a large number of NPC's (ordinary students without a soul), those students and teachers of the school that Yuri considered "common characters" are not human, but look and act like these. Another organization in the SSS is the Guild, which is far below the surface of the school, which serves to supply the weapons that the SSS uses against the Angel. Any person in the afterlife is capable of creating anything from ground if that makes you remember of your past life, and the Guild uses this ability to mass produce weapons.