Yuuichi Aizawa is the main protagonist of Kanon. He is friendly and outgoing, and though as nice as of a person he is, he has yet to learn the sensitivity of women. He constantly teases the main cast of girls throughout the story which varies in severity depending on the girl. Despite this, he does have a soft side that likens him to an older brother as noted by Shiori Misaka. He used to visit the city in which the story takes place, but his memories of that time are gone, slowly coming back to him as he interacts with the people he met in the past. As noted by himself, he is afraid of heights.

While not aware of it at first, Yuuichi slowly begins to take notice in the supernatural events occurring within the city. During these times of revelation when he will discover something outrageous, he stays strong with the girls he has made close friendships with. Since Yuuichi is a normal person, he tries to help them anyway he can and will usually go out of his way in order to protect one or more of these girls.