Oyayubihime Infinity Vol 1

Oyayubihime Infinity Vol 1 by Toru Fujieda. A Romance manga rated Teen, published in English by CMX in 2006.

Kanoko has a butterfly-shaped birthmark on her left hand, and when a boy named Tsubame shows up convinced she is Agemaki, his one true love, her world turns upside down. As the two meet other teens with similar birthmarks and stories of their own, Kanoko starts falling for Tsubame, even as she begins to wonder whether they are really meant to be. A bittersweet shojo romance about fate and reincarnation.