Angel Beats! takes place at a high school acting as a Purgatory,  where students learn to give up any lingering attachments they still  have from life before continuing to an afterlife or reincarnation. While  the injury or cause of death are gone, those in the afterlife school  can still feel pain or other things as they did when they were alive, as  well as dying again, only to awaken with no injures several minutes  later. The story follows the main protagonist Otonashi, a boy who lost his memories of his life after dying. Upon awakening  in the afterlife, he meets a girl named Yuri who invites him to join the  Shinda Sekai Sensen (SSS) (死んだ世界戦線,  lit. Afterlife War Front), an organization she founded and leads  which fights against God for the cruel fates the SSS members  experienced in life. Their only enemy in the world is the school's  student council president Angel, a being with supernatural powers who  fights against the SSS. Yuri believes that anyone who follows Angel's  orders and behaves like a normal student at the school will eventually  disappear and pass on. However, those who fulfill their dreams in the  afterlife will pass on as well.
In the SSS, there are two sub-divisions which help in the SSS's  operations against Angel. The first is a four-girl band named Girls Dead  Monster whose objective in the SSS is to cause a diversion from other  activities the SSS is engaged in, while on the surface appearing to be a  normal all female band. This  includes distracting Angel and a large number of "normal" students and  teachers at the school Yuri deems "non-player characters" as they are not  human, but look and act the part. Another organization in the SSS is the  Guild, located far below the surface of the afterlife world, which  serves to supply the weapons the SSS uses against Angel. Anyone in the  afterlife is able to create anything out of dirt that they had memories  of in life, and the Guild uses this ability to mass produce weapons.
Angel uses a similar ability to create her supernatural powers known  as "guard skills", with the aid of a computer program called Angel  Player. The primary one that she uses is called "hand sonic", a blade on  one or both forearms that is capable of changing into five different  forms. Other skills include but are not limited to: "distortion", an  invisible barrier that deflects bullets or other projectiles away;  "delay", which creates an after-image to disorientate an enemy in close  range; and "harmonics", where a clone with a consciousness of its own is  formed from the original. These abilities are activated by voicing  their name; however, others like "overdrive", which gives her great  physical strength, are passive and are always on.
The Guild is purposefully destroyed after Angel infiltrates the  compound, but the Guild members relocate to the old Guild location,  which Angel does not know about. As Otonashi begins to get used to life  in the afterlife, the leader of Girls Dead Monster, Iwasawa, disappears  in front of a crowd of people after a solo musical performance. The SSS  find out Angel's real name is Kanade Tachibana, and after a successful  operation, Kanade loses her position as student council president and  the vice president Naoi succeeds her. Unlike Kanade, Naoi cracks down on  the SSS and even uses powers of hypnosis  to control NPCs to fight for him. Otonashi is able to stop him after  acknowledging Naoi's existence and Naoi subsequently joins the SSS.  Otonashi regains his memories with the aid of Naoi's hypnosis and agrees  to continue with the SSS.
With Kanade a normal student now, Otonashi befriends her and invites  her to join in on SSS activities. Kanade uses one of her powers to clone  herself while engaged in combat, resulting in a violent red-eyed Angel.  The clone replicates itself many times, but the clones are later  absorbed back into Kanade after Yuri rewrites the Angel Player program.  Kanade manages to overcome the personalities of the violent clones after  awakening from the ordeal. Otonashi starts cooperating with Kanade to  help the other SSS members move on after he fully remembers the details  of his life and death. Kanade is reinstated as student council president  in accordance with their plan. Otonashi and Kanade cooperate to allow  Yui to pass on by fulfilling her wishes, but it is Hinata in the end who  fulfills her final wish to get married that allows her to pass on.
Mysterious shadow monsters appear and begin attacking the SSS.  Takamatsu gets devoured by one, only to reappear as an NPC. Otonashi  reasons with the other SSS members and many of them agree to pass on in  lieu of becoming an NPC, including the rest of Girls Dead Monster, Chā,  and several unnamed members. Yuri notices that the NPCs are turning into  the shadows, and her investigation into who is behind this leads her  back into the Guild. After receiving help from Otonashi, Kanade, Hinata  and Naoi, Yuri meets a boy who tells her he was programmed to activate  the shadow program when love was detected in the world. The programmer  himself turned into an NPC long before. Yuri destroys the computers  responsible for the shadow program. Three days after the incident,  Otonashi, Yuri, Kanade, Hinata and Naoi are the only ones yet to pass  on. They hold a graduation ceremony where they thank each other for  their support. After Naoi, Yuri and Hinata pass on, Otonashi learns that  Kanade's regret was not being able to thank him for the heart she  received from Otonashi after his death. Otonashi is heartbroken after  she thanks him and passes on, as he has fallen in love with her, but he  too passes on shortly after. In an epilogue, Otonashi and Kanade meet  again in the real world.
