Akari is Hiroyuki's childhood friend. She will almost always go to wake Hiroyuki up in the morning to go to school. She is especially fond of teddy bears, with special emphasis on the one that Hiroyuki gave her during their childhood. Both Akari and Hiroyuki have known each other since kindergarten and they are extremely close. She is very much in love with Hiroyuki and spends a lot of time around him. Akari likes to call Hiroyuki with the -chan suffix attached, despite his occasional protests. Akari is very adept at cooking and is a member of the school's Cooking Club.
In the game she is just one of several female characters, but in the anime she adopts a central role, acting as narrator, with her romantic aspirations forming the main recurring theme of the series. In one episode (#7) she actually supplants Hiroyuki as the main character when she befriends the psychic girl Kotone: in all other episodes it is Hiroyuki who befriends the "guest" character of the episode. (In the manga Akari has a less pivotal role (though still a major one), and it is Hiroyuki who befriends Kotone.)
In To Heart: Remember My Memories, her normally optimistic and somewhat naive personality takes on a more depressed and emotional tone when Hiroyuki begins to pay less attention to her and more to the android Multi, and her relationship with Hiroyuki nearly fell apart.
The long term influence of To Heart and Akari Kamigishi on otaku culture is illustrated by the character design of Tsukasa Hiiragi from the manga and anime series Lucky Star. Tsukasa's look, complete with trademark yellow ribbon, appears to have been based on Akari; a fact that has been mocked a few times within the series.