Be There With Me When I've Fallen
Prologue: The Vendetta of Heaven and Hell
Back in the 13th century, the angels and demons have been neutral to each other for many, many years. But now, in the present 20th century, a vendetta has been created between Heaven and Hell over a mere mortal. And it just happens to be Haruno Sakura, a human who bears a secret, a secret that will forever be marked against the rules of the two worlds.
When the angels heard about it, they were sunk into desperation. Conflict wasn't really their most favorable solution for this matter. But, on the other hand, the demons were ecstatic, since there would be bloodshed involved.
They're immortal, so they can't die, but they can feel pain once they step inside the planet called Earth. They will be given human bodies and they will roam around until they find the human.
Many of them were confused about why it was so important for them to find a lowly human girl, but they disregarded that thought and cared only about their mission for they don't want to disappoint their masters.
Meanwhile, a certain girl was worrying about her own matters in Earth, oblivious to the fact that immortal beings are fighting each other just to find her and take her to their respective worlds.
When the sun rose the next morning on Earth, the search begun.