Maiku Kamishiro's background has always been a source of difficulty for him. An old image of two young children, a boy and a girl, playing in a little pool outside of a blue house is the only indication he has as to who his family could be. In an effort to locate his family, he relocates to this blue house and begins working as a programmer. He's having a happy life until two very different girls come up at his door, both holding the same photos and claiming to be his twin. With no means of knowing who is a relative and who is a stranger, Maiku lets both girls live with him until they can be sure.