Meet Nipori Ayumu, an 80 year-old man, who, due to a serious heart condition, has spent sixty years of his life confined to his house. One morning, he wakes up believing himself to be twenty again. In his mind, he has become the youthful young man that he once was. However, reality fails to keep up with his illusion, and everything around him seems to be quite different from what he is used to. So, he decides that he is simply dreaming. As his reality becomes his dream, his unhappy world turns into a life enriched with happiness and expectations for the future. Ayumu is now enjoying his life to the full again.
Meet Kodai Narisu, an 18 year-old home-care worker who is newly assigned to look after Ayumu. To his great surprise, Narisu looks exactly like the girl he had fallen for when he was twenty and he immediately mistakes Narisu for her.
Narisu, on the other hand, is trying to deal with her own secret love. She is living amidst the uncertainties of youth, struggling to find her way.
Ayumu's happy dream. Narisu's fragile and sometimes painful reality. The story takes place in an old house, where these two contradicting worlds intertwine with each other through their words and exchanges. Ayumu gradually begins to realize what is real, until one day, he decides to find out whether what he believes to be his life is in fact a dream.