Ai Ooto is forced to deal with her new world after her closest and only friend, Koito Nagase, commits suicide. With nothing else to live for, she follows the directions of a mystery entity and is persuaded to buy an egg, especially a Wonder Egg. Ai is charged with protecting people from challenges after breaking the egg in a world that materializes during her sleep. She feels that by doing so, she has come one step closer to saving her dearest buddy. With this perilous yet alluring possibility in her hands, Ai enters a world where she must identify the connection between other people's demons and her own.