The story follows the life of Ganta, who is just a 14-years old student when all his classmates are murdered by a mysterious man. Ganta is accused for the crime that he didn't commit. He goes to jail because of his lawyer. The lawyer shows a modified tape in which Ganta admits that he is the murderer. Ganta is sentenced to death, entering the prison named Deadman Wonderland.
He has been there but as a tripper. This prison is private and serves as an amusement park. Baside the brutal games, there is a secret corner in which games of life and deth are played. Only people with special abilities can participate in these battles. They came to being ten years ago after an earthquake which destroys most of Tokyo. ganta's survival is at question, because if he doesn't eat a candy filled with antidote in the next three days, the bracelet on his neck will kill him. Sadly, the vice-principal has a thing against him and this brings Ganta directly in the battles of life and death.