Abandoned by his mother, growing up in different orphanages, the only thing Kamishiro Maiku has left from his early childhood is a photograph showing himself in front of the house he used to live in and a girl playing in a children's pool.

When Maiku recognizes the very house in a TV report on an UFO sighting, he decides to travel to that peaceful town. Trying to recollect more of his childhood memories, he starts to live in the house there all by himself.

One day, however, Miyafuji Miina and Onodera Karen burst into Maiku's life. Both share his eye colour, both of them also have a copy of the very same photograph, and each one of the two girls introduces herself as Maiku's long lost twin sister...

But who is actually Maiku's twin? And who is the childhood friend Maiku will be able to fall for?

[Source: AniDB]