Angel Beats! is a mixed-media collaboration between key, Dengeki G's Magazine and Aniplex. The show takes place at and around a high school where teens who died unfair deaths are given second chances to fulfil their dreams and give up attachments. The story follows Yuzuru Otonashi, who wakes up in the world and agrees to join Shinda Sekai Sensen, an organization consisting of students that do not want to move on. Yuri Nakamura leads the group in a fight against Angel. Yuri believes that anyone who follows her orders and behaves like a normal person will disappear. This includes going to classes during the day and generally acting like average students. Yuri and the group (abbreviated to SSS) do not wish to give up their second chance at life by disappearing. Thus, they try their best to not act like regular students and try to eliminate Angel.
There are two other divisions that help out the SSS. One of these is Girls Dead Monster, an all-girl band that performs concerts to distract students so the SSS can execute missions. The band is headed by Iwasawa, who is the lead singer and rhythm guitarist. The other division is the Guild, a huge underground factory that mass produces weapons for the SSS.
The groups enemy, Angel, is a mysterious girl who is capable of using different skills during fights.
The determined leader of Shinda Sekai Sensen. Yuri recruits Otonashi at the beginning of the show. She is proficient in the use of close-to long-range weapons from a handgun to the CheyTac Intervention sniper rifle. She also knows some hand-to-hand combat as well. Before her death, she was at home with her three sisters when robbers broke into the place. They told her to fetch the most valuable thing in the house for them, or one of her sisters would be killed every ten minutes. She frantically searched the entire house and ended up finding a large vase in a room. She figured it would be worth a lot, so she picked it up and started heading downstairs. Unfortunately, she fell down the stairs and the vase shattered. All three of her sisters were murdered but she was spared. She is angry at God in the afterlife because she couldn't save her sisters.
Otonashi is the protagonist of Angel Beats. He wakes up in the afterlife next to Yuri, who recruits him into the SSS. He had a very difficult childhood. His only sister, Hatsune, was diagnosed with a terminal illness and spent her last days in a hospital bed. Otonashi took care of him as much as he could until her death, which devastated him. One day, he got into a terrible train crash but survived. Along with another person, he managed to take care of the survivors for as long as he could despite them being completely trapped in a tunnel. Right as they were about to be rescued, Otonashi died of his injuries. Before he passed away, he took out his license and became an organ donor.
Angel is the enemy of the SSS. According to Yuri, anyone who follows her orders and acts like a normal person will disappear. Because of this, the group perceives her as hostile. They often attempt to kill her, but never succeed. Eventually the group manages to get her fired from her Student Class President position, which clearly depresses her. Otonashi feels sympathetic and realizes that she really isn't their enemy, partly because all of her skills are defensive and not offensive.