From ShoujoMagic:
Living in regret that his formula gave birth to the atomic bomb, Professor Einstein sends two boys whose eyes can see the future on a train that travels at the speed of light before embarking on his own final adventure: death. His hope is that they will find "HER" and tell her his wish, for it is only she who can grant it.
Fifty years later, it is 2005 and the place is Tokyo. At last, "SHE" (Ruika) has been found... but Ruika has an unusual circumstance. For her mother's sake, she's been living as her dead brother since childhood. Does Ruika truly have the power to grant wishes? If she grants her mother's wish by becoming a boy, then no one can lead us into the GLOBAL GARDEN. Now it's a race against time and against each other, because everyone has a dark past and an ulterior motive for possessing the girl who can grant Einstein's wish.