 The story revolves around Kōhei Orihara , the main protagonist . His father died when he was very young , followed by his younger sister Misao and finally his mother . Deeply depressed , he goes to live with his aunt Yukiko , his mother 's younger sister , about ten years before One 's story begins on November 30 , 1998 . After he meets Mizuka Nagamori as a child , Kōhei begins to <unk> himself in the Eternal World , a world within his mind . The game 's main recurring motif is a focus on the Eternal World , a mystical alternate space which is never clearly explained , and the details of which are unknown . Shun Hikami 's remarks in the original game are possible clues about the Eternal World . 
