The existence of Alter User is due to "The Great Uprising", a nuclear-like event that caused a complete change in the social, economical and political structure of the society that was affected by it. So much so that it caused a drift between people who accept the new social system that is trying to be implemented and the people who refuse to adhere by it. There are Native Alters (who live outside the rule of the government in a place called "The Lost Ground") and Alters who have joined HOLY, which is an organization composed of Alter Users to control Alter Users.
The series mainly dwells with the hijinks of the two main characters: Kazuma and Ryuhou. Their personalities differ drastically, as Kazuma is basically your stubborn yet good-hearted character while Ryuho is your cold and determined but strong and just character. Although, they become bitter rivals, as the series progresses, they become more and more aware of the fact that they are more similar than they think since both have things they want to protect.
All in all, a great 26 episode series which is entertaining all the way through and has a solid ending. Recommended.
"It's not dying that I'm afraid of... It's dying without accomplyshing anything..."
s.Cry.ed was broadcasted in Adult Swim a while ago but go get your hands on the series!