 Maiku Kamishiro is a high school boy living by himself and trying to make ends meet by working as a programmer. He owns a photograph of himself as a young boy along with a little girl whom he believes is his long-lost twin sister. One day, he meets two cute teenage girls - Miina Miyafuji and Karen Onodera - who possess the very same photograph. Miina, and Karen even have the same eye color as Maiku. After much confusion, Maiku finally allows the two to stay in his house until he can find out which one is his real sister. On top of that, he must fend off the advances of his peers, including the class president and a homosexual classmate.