Devil Devil

Devil Devil or Devil & Devil (デビデビ Debi Debi?) is a manga series created by Yūki Miyoshi.

Plot
The demon Sword and the pure Ios are fighting their 101st battle during one of the many wars between pures and demons, when, both severely wounded, they fall on Earth, where each of them has to take the body of a human to survive; they are surprised to see that the bodies they take are those of two twins, and, to make things worse, the angel has taken the body of the violent rebel Kanna, while the demon has taken that of the weak and defenseless Soma.

Other Sources

 * Devil & Devil
 * http://www.animenewsnetwork.com/encyclopedia/manga.php?id=2899
 * http://www.mangaupdates.com/series.html?id=1161