It is ten years after the greatest crisis in the history of mankind, the Great Collapse. The setting is a huge school campus-city known as Academia, the symbol of rebuilding from the disaster. While Shiratori Kuu, a high school student, lives her school life, she feels that there's something lacking in her unchanging and unchangeable self. Every now and then, Kuu would have the same dream about a prince who'd come and see her. At the school festival, a boy who looks exactly like the prince in her dream appears. His name is Ayanokoji Kyoshiro, and he says to her the same words as the prince in her dreams – "Let's go together."