To view all plot lines in their entirety, the player will have to replay the game multiple times and choose different choices to further the plot to an alternate direction. After Mai's scenario is completed, a replay of her route will offer an additional choice to play through Sayuri's back-story. Jun Maeda, who worked on the scenario for Kanon, commented in March 2001 that the Japanese public may have fallen under the impression that Key makes soothing games because of Kanon's influence, but Maeda affirmed that there was not one person who worked on Kanon who thought that.
In the adult versions of the game, there are scenes with sexual CGs depicting Yuichi and a given heroine having sex. Later, Key released versions of Kanon without the erotic content. The versions that include the adult content have one explicit sex scene in each of the five main story routes, in addition to one fantasy scene. Outside of these, there are two scenes with nudity. Yūichi Suzumoto, a scenario writer who worked on later Key titles, commented that the sex scenes in Kanon are very self-contained, and can be easily removed without altering the story. Maeda remarked that the sex scenes were not written with reproduction in mind.
Plot
Setting and themes
There are several important locations featured in the Kanon story, though the location names are seldom mentioned explicitly in Key's works. The events of the story occur during winter, and since it often snows periodically over the course of the entire story, the city is always presented covered in a layer of snow. The shopping district is featured throughout the story when the characters go into town, and especially whenever Ayu appears in the early story. The high school where Yuichi and the other main characters attend, including the school grounds, is shown predominantly in Shiori's and Mai's stories, and is otherwise a general setting where Yuichi interacts with other characters.
There are recurring themes that appear throughout the story. A music theme is present, as the episode titles from the 2006–2007 anime have parts in their titles related to music, such as overture and introit. Miracles play a large part in the story; Kanon's plot line and characters are influenced by various instances where miracles occur. The act of promising and keeping promises is found throughout the story. Yuichi eventually makes important promises to the five main girls while at the same time fulfilling past promises he had made with four of them when he used to visit the city as a kid.
One of the motifs in the story is amnesia, or memory loss; three of the main characters—Yuichi, Ayu and Makoto—suffer from amnesia in varying degrees; this is used as a plot device to advance the story. Another motif deals with the favorite foods of the five main heroines. Newtype USA stated in an article on Kanon that "it's when the characters are eating something really tasty that they seem most beautiful and alive", despite the somber setting and overall tone of the series. These five foods of choice are: taiyaki (Ayu), strawberries (Nayuki), nikuman (Makoto), ice cream (Shiori), and gyudon (Mai).
Principal characters
The player assumes the role of Yuichi Aizawa, the protagonist of Kanon. He is a cynical 17-year-old high school student, and is known to play jokes on the girls his age he knows and interacts with throughout the story. Despite this, Yuichi is very loyal and will go to great lengths to please others, even at the expense of his own time and money. He generally has a selfless personality and does not ask much from others in return for what he does for them. Ayu Tsukimiya, the main heroine of Kanon, is a short, strange, and mysterious girl immediately recognizable by her winged backpack, red hair band, and tendency to refer to herself with the masculine first-person pronoun boku (僕). She has a fondness for eating taiyaki, and is notorious for her catchphrase, "ugū" (うぐぅ), which she mutters as an expression of various negative emotions such as frustration, pain, and fear. Yuichi's first cousin Nayuki Minase, another of Kanon's heroines, has been in love with him since childhood, and must learn how to deal with her feelings, especially with the threat that he may fall in love with one of the other girls. Nayuki talks noticeably slower than those around her, and has constant trouble waking up in the morning except on a few occasions when she is up before Yuichi, much to his surprise.
Yuichi is accosted a few days after arriving in the city by Kanon's third heroine Makoto Sawatari, a young girl who has lost her memories, but despite this she is sure that she holds a grudge against Yuichi from when he last visited the city. Makoto has a mischievous side and constantly plays pranks on Yuichi. She has an affinity towards the spring and once wished that it would stay spring forever. Yuichi coincidentally runs into Shiori Misaka, another heroine and first-year high school student suffering from an unexplained illness since birth. Her affliction has caused her to become very physically weak, and she is almost always absent from school because of it. She tries to be strong in the face of her condition, and gets along well with others, even though she does not know very many people her age due to her condition. The fifth and final heroine in Kanon is Mai Kawasumi, a third-year student of the same high school that Yuichi attends. She has a cold attitude towards almost everyone, but despite this, she is actually a very kind and caring person; she "punishes" someone who makes a playful joke about her by giving them a light karate chop to the head.
