Yuichi Aizawa is a second-year high school student who visited the city where the story takes place seven years before Kanon's beginning. The story opens on Wednesday January 6, 1999 when Yuichi arrives in the city and is very detached from it and its inhabitants. Before his return, it is decided that he is to stay with his first cousin, Nayuki Minase, and her mother, Akiko. After his long absence, Yuichi has forgotten almost everything except minor details of what happened seven years before and needs to be reminded of what he left behind. Nayuki initially tries repeatedly to jog his memory but is unsuccessful. Throughout the story, as he learns about the supernatural undertones of the city, Yuichi is reminded of the events of seven years ago.
