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.