Kanon is the story of a boy named Aizawa Yuuichi. Seven years ago Yuuichi lived in a small, quiet town with his parents. Unfortunately, their jobs kept them on the move, and soon Yuuichi had to leave. Before he left, he met a young girl named Tsukimiya Ayu, who quickly became his friend.

Now, seven years later, Yuuichi returns to this small town to live with his cousin, Minasae Nayuki. But, oddly enough, he can't seem to remember anything from seven years ago. He meets two people two people that already seem to know him, Sawatari Makoto and... Tsukimiya Ayu! Is this same girl from seven years ago? Yuuichi will have to piece together his memories in order to find out.