Miko is a nineteen-year-old girl working part time at a local shrine as a shrine maiden. She claims that her name, "Miko," corrisponding with her job as a shrine maiden ("miko" in Japanese) is a coincidence. At the beginning of the story, she is involved in the hunt for the Platonic Heart, fueled by the wish to have true friends. She later drops out of the contest after meeting Aya and Natsume because of the fact that they become her first friends.

She later goes missing, thus causing Aya to join the contest for the Platonic Heart in hopes that if she wins, Miko will be found.