The story is mainly revolving around three high school students: Maiku Kamishiro, Karen Onodera, and Miina Miyafuji. The three were drawn together by a photograph of their childhood home which later makes all of them seek out the house in the picture. However, the picture only has two children - a boy and a girl. Hence, only one of the girls, Karen or Miina, is related to Maiku. The only other identifying feature of the pair in the picture is that the boy and the girl have eyes of the same unusual color; a feature that furthers the ambiguity as all three of them have the same eye color.
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